I have my own domain (herohog.com) and unlimited email addresses under my domain which allows me to use a unique email for every site that requires an email address. This way I know exactly where someone got my email address from and I can take action against those who would SPAM me. I also have gmail accounts, a Yahoo account and a Windows Live account (or two). I have those mainly for their IM clients.
For Instant messaging I use Trillian which allows me to monitor/use the following IM services all at once through a single client!
AIM: herohog
Astra: herohog
Facebook:
http://www.facebook.com/HeroHogGoogleTalk: herohog
ICQ: 442712703
Jabber: herohog AT programmer-art DOT org
MSIM: herohogLive AT herohog DOT com
MySpace:
http://www.myspace.com/545910607Skype: herohog
Twitter: herohog
WindowsLive: herohog AT live DOT com
Yahoo: herohog
NOTE: Skype does require it's own Client but does use Trillian's interface for Chat.
Trillian supports several other clients that I don't use in addition to the ones I listed above! I use the PRO version but the standard version is great and unless you want to do video will be fine for most people.
No, I have no interest or association with Trillian, I'm just a very happy client of theirs and if you, like me, have several accounts on several services and are tired of having 15 different apps using up your reasources and desktop space, it is the way to go IMO.