Hmm… Just playing around with TinyCore, a tiny Linux distro: the download comes to only 10MB!
Well, if you want some additional functionality, then you have to download and install stuff, of course. But still, I quite like it. Simple, clean GUI. Also sports a 2.6 kernel and not just 2.4 like DamnSmallLinux.
By default, it runs from the ISO image (can be run from a USB pen drive!), but following the instructions here, I installed it permanently within a VirtualBox instance. The next step will be to install VirtualBox’s GuestAdditions, but that might take some more effort, having to install gcc, etc. We’ll see… 🙂