I've been using GLoop with great success. Its very simple single track looper with overdub. I tried mobius as well, but it is too much to learn for the basic looping I need w/ my band. You can check it out here: http://www.gvst.co.uk/beta.htm
I'd recommend mobius if you need something more robust but try out GLoop, I found it to be exactly what I needed.
I play lead guitar and in a few songs I play some synth leads so I've hooked up a single GLoop to both amplitube and and my synth (u-he Tyrell n6) This works really well. I use an Arturia MiniLab 25 key mounted to my mic stand, a FBV Express MkII (4 switch foot controller) and an FBV Shortboard MkII (13 switch foot controller)
I use the minilab to control the synth, the shortboard handles turning stuff on/and off in amplitube and switching presets. The Express I use to control GLoop. I have one switch for record/overdub, one for play/stop, one for undo last, and one for reset all. Both amplitube and Tyrell run into the same instance of GLoop that way I can play and record a synth lead, loop it and switch back to guitar, or play a guitar rhythm, loop it and then play a guitar lead over top. I can even play guitar, over dub synth, then over dub more guitar.