Or at least, an adapter to utilise some power supplies you may have lying around. AS it stands, this is most likely useful for anyone living in PAL land. This is because I made an adapter to use a PAL SNES power supply and a 2amp USB wall charger. PAL SNES supplies output 9V AC, instead of 9V DC like the NTSC ones.
This set up has worked well so far, but it's early days. ran for maybe 8 hours straight, no software. Then I went to a friends place and borrowed some carts and tapes. Then ran the C64 for a few hours with a game loaded and title screen music playing, therefore giving the 9VAC side of things a bit of a workout (SID chip and tape drive). I see no reason why this won't keep working, and in fact it should be more reliable and safer than the original supply.
So if you have a C64 and the power supply has died, and you've googled and googled until you know less than when you started, I made a little web page, that tells you how to do it, without having to read 5 different twenty page threads full of Mr Electrical Engineers postulating about this and that (",)
http://dannygalaga.com/c64.html