Ok, how many instant messaging ids do you have? I know it's more than one. More than 3? How many clients do you have running right now? I tried a couple of hacks for more than one AIM screen name (supported by AIM now). Then I had to run MSN Messenger (or was that Windows Messenger?). And yahoo? And every now and then, you want to connect to an irc channel?
Why don't you try gaim? It lets you connect to all of these messaging services at once, even with multiple ids on each service.
But wait, there's more!
You can make your buddy window always on top, even transparent if you want. There's even a docking buddy list "crawler." Then there's the concept of "buddy pounces." What these are are actions to take when a buddy changes state. Say you want to send your friend a message when he goes from idle to active but you may not be there. No problem. Just setup a buddy pounce and you're done. The action can be to send a message or to just play a sound on your end.
Chat windows can be tabbed like Mozilla. You can separate them and then put them back together.
The thing I like best is that you can set it up so that every conversation is logged. I can go back and search through my logs for URLs that I've exchanged with my friends.
Did I mention that there are no ads?
There are lots more features but those are the biggies. Go read up on it, download it, and play with it.