I used a p133 with 96mb of mem for 6 years. Of course at the time most GNU/Linux coders actually had a clue about writing streamlined software. This seems to be a harder and harder skill now-a-days. So I'm becoming more and more picky about what software I run.
I'm just glad I can always find something to fall back to and not need all those resources.
Examples:
http://kazehakase.sourceforge.jp - my main browser now for 3-4 years or so
http://www.uzbl.org - A very promising browser project I plan on using as soon as it get's some more functionality
http://www.fvwm.org/ - my window manager for the last 3 or so years - I started with this more than 10 years ago and in between tried all the others and now am back to this
http://www.mpg123.de/ - insanely optimized mp3 decoder. This will run on a p100 at ~30-40% cpu usage compare that to MAD which is what tends to be used with it's 60-70% cpu usage and you get a clue.
Hallmark of all these projects? Low resource usage which tends to be the result of good coding practices.
I constantly search for such projects. Why can't people still code like they have 32mb mem available and a p100 machine. It would improve general power use and improve overall performance.
Sadly even those that have such constrained environments i.e. cell phones running ARM and so on seem to think they can throw away resources. A few apps on my cell phone can make it get so hot due to usage that it's annoying to handle.