If you're a *nix guy you should be able to get a lot of stuffs working in N900, the stuffs that don't have fancy UI and absent from other phone. That's where the real fun is.

You might disagree with me, but N900 is not the kind of phone that preloaded with full set of well-cooked fancy applications off the shelf. Seriously and without any offensive meaning, from what you just described, I believe you should get an Android phone. I'd recommend HTC Desire Z, its look resembles a N900, with a robust hardware keyboard. (though I feel it running slower than N900, maybe I'm mistaken.)

And if you are going to sell it real cheap, tell me.