I use Evernote. It OCRs text out of photos I take on my iPhone. I try to take a photo of anything which gave me an idea, and usually looking at the note is enough to trigger the idea again. That text is searchable.
I take pictures of whiteboards whenever I've been doing design. It can't OCR my handwriting well, so I usually use the iPhone's text entry to tag it with a few words before I save the note.
I agree with Evernote, it is awesome in so many ways. Moreso for retrieving stuff you read 12 months ago. I rarely add my own notes, but you can do that.
But as good as it is, it could be so much better, its search engine is really quite bad, not to mention the UI. But its by far the best thing I've found, I love it.
I take pictures of whiteboards whenever I've been doing design. It can't OCR my handwriting well, so I usually use the iPhone's text entry to tag it with a few words before I save the note.