I recently spoke with a customer who was not happy with our DB2 documentation. I'm actually pretty fond of the Information Center myself, I find the search capabilities nice. However, if you need to search for a DB2 topic and you aren't sure where to start. The IBM Software Support Toolbar is a great gadget. I've added mine to my FireFox browser and it's located right underneath my Google toolbar. I use both of these toolbars quite often. The IBM toolbar will allow you to search through all documentation, APARS, troubleshooting docs and learning docs with one click of the button. It also provides quick links to valuable support resources such as, Passport advantage and ESR (Electronic Service Requests).
It's a handy tool in a day and age of information overload. I find the toolbar a valuable asset. The toolbar can be used for other IBM support products, such as Tivoli, Rational, Websphere and Lotus. I've focused my conversation about the Information Management since DB2 is where I tend to spend most if not all my time.
If your interested in obtaining the toolbar you can download it for free from: