I record quick ideas as videos on my cell phone basically.
But for more functions...can't praise the Zoom R-16 enough. It ain't small but it's a portable 8-track with good internal mics and phantom too, great preamps, works as a soundcard, records on SD cards, produces perfectly aligned multitracs easily to any DAW software...and it has guitar amps and effects too...just an insane device. It alone can do more than a million-dollar studio in the early eighties. It's a bit large to carry around everywhere, but very light anyway; not suitable for quick to-be-remembered clips, but that's what a cell phone works well for IMO.
It ain't super cheap, but it's so good...and no need for any other soundcards etc. I've recorded a couple of albumfuls already with it and soon will release a live album completely done on it...here's one of our training tapes, recorded with it in training:http://deeaa.pp.fi/spookbox/2012/22_1_2012_nwyt_live.mp3
We've started to record all our practices; just 8 mics to board, my JMV head offers a D/I out as does the bass amp; then we mic the other guitarist's cab and my vocals via a tube preamp and drums are left with four; kick, snare and overheads. Everything bleeds into open mics nicely and creates a live feel.
Then I just take out the SD card, open cubase and import to a project I have made for it, and voilÃ¡ I have a completely ready-mixed version of the song/songs right there. Because we don't change mic positions or sounds meanwhile, I never have to mix 'em more, and if I do improve it, they're all in the same project and all get the same corrections easily. Superb system. I'm releasing a CD of the tapes with 13 live songs done just this way, all thanks to the Zoom R-16.