I'm looking for a tool for notes in Windows environment. We have a small developer team and we would like to have some kind of notebook in our desktops (open all the time) and everyone could add notes to this file/tray. What tool would you suggest?
Microsoft OneNote may be overkill, but it's designed specifically for your use case.
You can store the notebook on a network share, Sharepoint server, or (in Office 2010) on a Skydrive folder. Every edition of Office 2010 now includes OneNote (alongside Word, Excel, and Powerpoint). It's designed for multiple users to have notebooks open for editing simultaneously, with near-real-time synchronizing.
It also handles offline / online / sync scenarios, so you can record thoughts while away from the office.
It has an excellent search feature, and it even OCRs and indexes text from screen shots, scanned documents, and meetings recorded as audio.
Our development team has found it to be the best tool for our needs, both for development and production support notes. It makes it easier to locate documentation and to keep it up to date.
Disclaimer: Your mileage may vary.