Mal's Loop Recorder of choice (although my new Boomerang III pedal is rather amazing... see below).
The Akai Headrush E1 pedal is the looper (sample loop recording pedal) that I use. I find it better than the others as I'm into simplicity and spontaneity. It does 11 seconds with infinite layers or 22 seconds of just one layer. It doesn't degrade the signal as some of the others do. And it can cut back to the first layer. Akai have stopped making the E1 and replaced it with Headrush E2, which is pretty much the same except for 6 seconds extra loop length and a lovely blue hue. Yay! The alternatives include: Boss Loop Station RC20, which has lots of features, up to 3.5min loops, but has muddy/compressed sound and awkward inputting (if you stuff up, you have to erase it before starting again (whereas with the Headrush, you can just keep hitting the start button til you're happy)). Mihirangi uses a Loop Station to great effect, but has always struggled with the sound quality. The new RC50 fixes the sound problems a bit and adds features, but it's almost 4 times the size of the Headrush and there's an irritating glitch between recording and playback... why can't they get it right? Oh well, thankfully, the Digitech Jamman is very much like the RC20 Loop Station, but with better sound and more storage (though still with the restrictive inputting). I've got one now, but it's not going to stop me using my little Akai friend. There's also the Line 6 DL4 (good inputting, 16 sec max loop, nice green), Gibson Echoplex (a rackmount unit that does everything and is very flexible and adaptable, but thus very complicated) and Electro-Harmonix 2880 Super Looper. All the alternatives to the Headrush are more expensive.
I've also got a Korg Kaos Pad KP3, which is another beast all together (effect and looping). It's a lot of fun, but as a looper, it's very tempo based and thus a little restrictive. And it's a bit tricky to use hands free!
The Boomerang III http://www.boomerangmusic.com is amazing. Does everything the RC50 does and more and it's half the price, about a 3rd of the size and much better sound. Up to 4 separate loops, infinite layer, reverse, half time, copying sideways. It's about $500 if you buy it from the maker, who is releasing new software for it any day now (which will make it even better!). I still use the Headrush, due to muscle memory, but I highly recommend the Rang.
Loop recorders do great things for your timing, as you have to be very accurate with the buttons... it's like any instrument: You have to play it well. I only say this because I know of many people who were extremely frustrated when they first tried it and things weren't as easy as they seemed to be. It just takes practice. I've mucked around a little with softwear loopers, like Abelton Live and Fruityloops (now FL Studio), but I don't like to have a computer onstage. When recording, I loop things in Reaper, which is a brilliant, flexible and cheap recording software http://www.reaper.fm , which means you can pan and EQ things. Good luck! Cyasoon, thine a looping, Mal
P.S. The mic I use to use live was a Behringer XM8500, which is only around A$50 new! It's not too different to an Shure SM58, but has better bottom end and higher output level. Can be used as a pretty fine kick drum mic. And in the Oxo Cubans, we've made our brass bugs out of XM8500 capsules: Simple, tough and sound fab, particularly on the tuba. The XM2000s (with the switch) seems to have the same capsule, but they don't sound as good... different shape, I guess. I've just bought a Rode M1 which, while not as bassy as the Behringer, is brighter and more even sounding... and it's Australian made!
But the mic I'm now using live is an Audix OM6, which has superb bottom end (cleanly down to 40Hz) and nice tops than the Behringer. More expensive though... about $300.