Alesis's MultiMix 4 USB is an excellent tool for recording podcasts, sketching song ideas, tracking movie voiceovers, and more - not only is it a 4-channel desktop mixer, but it's also a stereo USB audio interface.
With the Alesis VX49 USB/MIDI controller keyboard, you can load up your favorite software synthesizers, samplers, and drum machines as if you were working on a standalone keyboard workstation.