Renee Blodgett on her blog Down the Avenue mentions Jupiter Research’s Eric Peterson three "must have tools" for the digitally-inclined. The functional areas are: Desktop Search, Instant Messaging, and Information Gathering.  Here are my thoughts (Windows centric) …

For desktop search I use X1.  I have been using it for a while and I see no reason to switch, even to a free one.  The new recent improvements have been helpful, and tech support has been excellent resolving a few problems I have found.

On the instant messaging front I agree with both Renee and Eric that Trillian is great.  The new version 3.0 has significant improvements to the interface and setup.  I highly recommend it.

In the information gathering area, I use a lot of stuff (probably worthy of another detailed blog post) but I can not say enough about ClipMate for keeping my cut-n-paste data collected, organized, and quick to utilize.  I am also part of the Onfolio 2.0 beta and it is a great improvement to 1.0.