My FX pedal has a pitch-shifter capability that allows you to play with two pitches +/-12, but you can switch it off and play with only one pitch active so you can emulate a bass, but it's not quite the same...I'd be surprised if you couldn't do this (or better) from a POD.

I'd personally say for a real bass sound, you need a bass guitar, but I understand why you're asking. I'd be interested to know if there is anything out there that gives you a decent bass sound from a guitar too...anyone? Rask - this sounds like your territory...