How can you find someone's instant message screen name?

Answer:

1. Ask

Ask them or someone who knows them.

2. Use Linux, or a program ported from Linux to windows:

I used a program called gaim on all my Linux boxes that has a feature where you can search for someone's sn by typing in their email address. It works great.

I now have yet another computer, this time with the latest windows installed. (I actually stopped using windows in the mid 90's for security reasons, but now need one for `backward compatability' - my new employer requires that I run his windows software.) I've already installed some Unix utilities ported from Unix & Linux to make using such a crappy operating system easier & more flexable to use, and it got me thinking, so I Googled "gaim for windows" and was taken to a page providing a version that has been ported to windows, (it's now renamed to "Pidgin".) I installed it on my poor windows box, and found that it works as well as it did in Linux. Now I can find my friend's screennames even though I'm using an overpriced, underfeatured, virus-prone, insecure, Micro$oft computer! So I'm happy.