I use three major ones, all for different reasons. I use MSN, which has a nice file sharing option. AOL I use simply because I've had it the longest and old friends can still find me. I enjoy yahoo because of the free internet radio.

All three are great in their own right, however, opening each program is a pain. So I started using Trillian, which opens each IM program you might use and shows you who is online for each in the same window. Simply click on the name of the person and IM as if you were using the programs seperately. Works with AIM, MSN, ICQ and Yahoo on the free version, possibly more with the Pro version.

Only problem I have is some of the options are limited, such as video conferencing, and the other more indepth options available with each IM program. It will give you notice when you receive new emails on whatever account you enter. I have had no problems with it since I started using it.

One nice feature of Trillian is the ability to send everyone in a contacts folder the same instant message. Handy for times such as:

1. You need backup at the reference desk

2. Printing is down, and you can't wait for people to learn about this in an email.

3. You've got a tough reference question at the desk, and you know that many heads are better than one.

4. You want everyone in the office to know that you just made a fresh pot of coffee.