You sing, you play guitar and bass, you record and play live, you play keys, and now you want a single USB device to handle everything in a single box. First, you're more talented than us. Second, you might want to check out Line 6's upcoming TonePort KB37. Announced at the summer music equipment trade show this weekend in Austin, this small keyboard includes controls for your fingers, inputs for footpedals for your feet, and uses software to model amplifiers, mic preamps, effects, and stompboxes, with processing options for vocalists and guitarists alike. Line6's equipment has plenty of competition, but it tends to be affordable and reliable. You may need to grow two extra feet and two extra arms to take full advantage of the thing, so Zaphod Beeblebrox, your audio gear has arrived.
Line6's KB37 Guitar/Vocal/Bass-Processing Keyboard [Create Digital Music]