I posted some screen shots a couple of months back with gkrellm running on the N900 - I may well have even posted a deb, though don't quote me on that, seems like a year ago now : )

Gkrellm does work, but it pegs your CPU at near on 100% so a lot of optimizations are needed to make it useful for Maemo - it compiles straight up in scratchbox, it just doesn't run very well.

Ahhh here is my post - I didn't upload anything other than a screenshot.