I don't really do that much "note taking" per se: for me it's more about recording ideas / quotes / so forth. On the go, I use a Moleskine like every other pretentious asshole out there, and at a computer I use Devonthink Pro: http://www.stevenberlinjohnson.com/movabletype/archives/0002... .

emacs org-mode

light-weight reminders: http://www.rememberthemilk.com

everything above that: 3banana - https://snaptic.com/corp/products/ (but I'm biased as you may infer from my username vs the guy posting about his company above).

full on docs: google docs

Textfiles in a dropbox folder so they are available on other machines and the iphone if needed.

Quotepad 2.2 on Windows

textfiles