Many communications professionals now regularly use Instant Messaging to correspond with clients, reporters, partners and co-workers for those one-to-one urgent matters where emails might get lost or are too slow. Since IM networks like Yahoo, AIM and MSN don’t interoperate, this can mean having several IM clients open at one time.
If you’re a Mac user, you might like to try out Adium, which allows you to log into several networks from a single application. I came across it from Om Malik’s 10 Mac Apps meme. It doesn’t offer the voice or video capabilities of Apple’s own iChat, and I’ve been told file transfer can be problematic, but it does cut down the number of open applications and have some fun extensions. It’s a bit like Firefox for IM at first looks. Anyway, worth taking for a spin.