Super Sonic?

For the first 5 years, the Doctor managed to get by without any particular tools or pieces of equipment. The First Doctor did have a ring which had strange properties - being able to open the TARDIS doors when power was drained by the Animus on Vortis, and useful for guiding a docile Zarbi in the same story. When he regenerated, this slipped off his thinner finger and he never felt the need to use it again.

Then, early in Episode 1 of Fury From The Deep, the Doctor produced the Sonic Screwdriver in order to open a gas pipeline inspection hatch. It appeared to be a stubby cylinder, about the size of a fountain pen, and it was simply a screwdriver - one that turned objects using sonic resonance. It fulfilled the same function in The War Games, when the Doctor used it to unscrew the grip of Lieut. Lucke's revolver - to prove they did not come from this time, and as a ruse to seize the weapon and effect an escape.

Between these two stories, however, we learned that the implement could do more than just help with the DIY. In The Dominators, it turns into a thermal lance - able to burn through a wall in order to reach a drilling hole down which the titular aliens were about to drop their atomic seed capsule.
The Third Doctor was cast in a Bond mould - with a penchant for different modes of transport and for gadgets - chief of which was the redesigned Sonic Screwdriver. The main difference was a strangely shaped headpiece.

The new Sonic was now used more as a form of key - able to open or close any kind of electronic lock. Two stories in particular demonstrate other attributes for the gizmo. In The Sea Devils, it can both detect and detonate land-mines, and the Doctor uses it to reverse the polarity of the neutron flow to sabotage the Sea Devil shelter's power supply. In The Carnival of Monsters, the Sonic demonstrates thermal qualities once more when it is used to ignite marsh gas - an event experienced by Professor Clegg when he handled the Sonic in The Planet of the Spiders. Of course the Sonic simply vibrates molecules - and vibration causes friction, which generates heat.
It is in the Third Doctor's era that the Sonic is first used as a scanner device - able to spot booby traps in both the Master's TARDIS and the Exxilon City.

With the Fourth Doctor, the Sonic continues to predominantly open locks - though the one at Fetch Priory is too simple for it, and the one in Borusa's study too complicated. The Doctor also uses it as a more general, all purpose tool for carrying out a range of repairs. Its heat generating properties were used to trigger the Zygon spaceship's fire alarm. Romana also had a screwdriver - one she made herself.
When John Nathan-Turner took over as producer, he felt that the Sonic Screwdriver - and K9 - were too useful. The Doctor should get out of trouble using his wits and whatever tools were to hand, rather than have these "get out of jail" cards. As such, early in the Fifth Doctor's era, the Sonic was destroyed by a Terrileptil.

After so many years, the Doctor felt it was like losing an old friend, but JNT stuck to his convictions and we would not see the Sonic again in the classic series. The Seventh Doctor did briefly use one, however, when locking up the Master's remains in The Movie.

The new producers were so keen to reference as many well known elements of the programme as possible - the Sonic, the Daleks, the Master, Skaro, jelly babies, the Eye of Harmony and so forth - that they forgot about the plot.
When the series returned in 2005, the TV landscape had changed. The new series would feature brisk 45 minute episodes (so no time for leaving the Doctor locked up for long periods) and there was a new eye towards marketing opportunities. Why couldn't every child (and quite a few grown ups) have their own Sonic Screwdriver? (In the same way, RTD vetoed the use of a specially designed TARDIS key, as any child could pretend that an ordinary Yale might be the key to the ship).

The new Sonic had a blue light, and appeared to be made of some kind of ceramic material as well as metal. Again, its chief purpose seems to be locking or unlocking doors, though it could also fiddle cash machines, scan for energy readings, and blow up Big Brother cameras. Its most bizarre new attribute was the ability to reattach broken barb-wire. We see the Doctor attempt to resonate concrete - but don't know if this would ever be successful as he's teleported away before he can finish. From now on, it can also upgrade companions' mobile phones to give them Universal Roaming.

The same Sonic continues with the Tenth Doctor. He has the annoying habit of frequently brandishing it as though it is a weapon. It still locks and unlocks but now seems to scan everything the Doctor comes across. Considering that it doesn't appear to have any kind of display screen, I'm not exactly sure how this works - though the Doctor does often seem to listen to it a lot. Does it have some kind of aural readout?  When the Sonic gets burnt out at the Hope Hospital, he gets himself another one. We'll find out later that the TARDIS makes them. Apart from general scanning and key duties, the Sonic once again can raid cash machines, as well as exciting the contents of a champagne bottle to pop the cork. A new attribute is to darken glass - whether it be the lenses of his sunglasses on San Helios, or astronaut visors in The Library. Sonic technology isn't unique to the Doctor, as Miss Foster had a sonic pen, and Toshiko Sato found herself a member of Torchwood after stealing the blueprints for a sonic device from UNIT.

The Tenth Doctor's Sonic is destroyed when the newly regenerated Eleventh tries to attract the attentions of the Atraxi. The newly rebuilt TARDIS gives him a new one - a much bigger version with a green light (the new production team having the same eye for merchandising as their predecessors). The Doctor once again seems to scan absolutely everyone and everything - waving it about almost instinctively - and again he brandishes it as though it were a weapon. In the climactic scene in The Day of the Moon - when Amy is rescued from the Silents' Time Ship - he actually uses it as such, whilst River sticks to an old fashioned ray gun. She, of course, has a Sonic of her own. Contained within is a neural relay which will enable the Doctor to download her into the Library mainframe when she dies. One new attribute of the Doctor's Sonic is the ability to sabotage guns - such as Silurian heat weapons. Quite why he has never used this function before we will never learn, or was it just lazy plotting on behalf of the writer? Talking of laziness, when it comes to the Sonic's locking / unlocking abilities, one thing that has always annoyed me is the way it opens the Pandorica. In the first part of the story, the cube is impregnable, but come the second part, Rory waves the Sonic and hey presto!
Which brings me to my conclusion. I have always thought of the Sonic Screwdriver as a wonderful concept, and when used sparingly works extremely well. However, in the last couple of years it has come to be used as the sort of universal problem solver which JNT always feared it had become - a sort of magic wand. I appreciate that the Doctor cannot be locked up for episodes on end as in the old days, but I would like to see him use his wits and ingenuity a bit more often - making use of whatever comes to hand. Whatever happened to solving problems with just a teaspoon and an open mind?