A while ago, I wrote down the random idea of using nanotechnology to generate a "master key" to prevent you from having a massive pocket of jangling and annoying keys when you have as many as I do.  It would be able to take three-dimensional impressions of your keys and regenerate them on command, utilizing little tiny robots... or carefully controlled magnetic fields and metal filings... or something like that.  Yeah, completely a pipe-dream, and way outside of the realm of our own current technological level, but I get remarkably tired of the sheer quantity of keys I sometimes have to carry around... and I know there are people who are much, much worse off than I am. 

Well, someone beat me to it with the Key-Port.  I admit, it is not quite nanotechnology...  More like those nifty little credit-card-holders on which you push the appropriate button and the appropriate card pops out - only for keys.  Apparently each little widget can hold six keys which slide out at the push of a thumb, in addition to the ability to support an RFID chip, an alarm remote, and an LED flashlight, all based off modular add-ons.  Not too sure about the RFID capability, since I confess I am not the strongest of fans of that kind of technology, but the ability to program in your car's wireless alarm/key-opener does have a certain attraction to it (especially since more and more keys can only be opened by those little fobs).  Unfortunately, you have to make copies of your keys to blanks that come with the Key-Port, such that there is a guaranteed fit and function, but that seems like a small price to pay to cut down on the jangle and confusion of a pocket full of keys. 

Even more unfortunately - the Key-Port is not yet available.  You can, however, sign up for a mailing list that will provide you with information concerning its eventual release, and all that good stuff.  Their forum/blog has some interesting comments from people who are interested in getting one of these, in a massively wide variety of languages - obviously being posted to such places as Gizmodo certainly helped their hit ratings.  So long as this thing actually is constructed and does not cost an arm, leg, and firstborn (unlike the now-ludicrous Optimus Keyboard), this could definitely be a nifty piece of lowtek technology. 

So, no, not quite nanotechnology, but it does avoid that annoying grey goo problem...