Evernote is a great application for note taking. I use this with my team to create a shared notebook of information. This is usually information that frequently changes or is too small to get filed into a Knowledge Base article or is just used for one time information gathering.
One of its best features for us was upgrading to Pro and having these notebooks cached on your mobile device for offline use. This is great for when you are onsite somewhere and need information, but don’t have the Internet for it.
Evernote can also take scans, emails, and files and does a great job of indexing EVERYTHING. It can even do OCR on images so you can search for text in the image (think business cards or scanned invoices).
There is both a free and a paid version. Both are great. I hope this quick plug was helpful. If you have questions, please reply to me on Twitter @thejedi.