Yojimbo - Yojimbo makes keeping all the small (or even large) bits of information that pour in every day...
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
HoudahSpot - Advanced File Search Utility for Mac OS X
NoteBuddy - Collaborate with others live using an online notebook.
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.