Apart from Puppy Linux I have also revisited DSL Damn Small Linux A tiny linux distro of only 50 mb. Yes, I know it is possible to make even smaller bootable systems but this one is ok apart from being one of the most populars out there.
DSL works great out of the box. The only problem I have encountered though the different versions is that I haven't been able to properly configure my printers. The script didn't work with my former Epson and it doesn't work with the HP either. Too bad, but it is a secondary issue for me as I only use DSL as a toy, similar to the way I use Puppy.
Puppy is more gorgeous and a bit more powerful for it includes more drivers out of the box. It also has a good package manager, similar to apt. Puppy is supposed to implement a debian compatible repository in a future release. Wait and see.