[cawhitworth]

Eclipse with PyDev with a Vi emulator (can't remember which one offhand). Having been something of an Eclipse skeptic in the past (despite being a Visual Studio devotee) I have to say I'm really quite impressed with it. It certainly makes navigating larger Python projects somewhat easier. Eclipse certainly seems no worse than VS for bloat or memory usage - although I guess that's not saying much :)

That said, if I'm just knocking out a single script or something, I'll just drop straight into vim.

(Oh, on Windows, almost exclusively)