Whereas with AOL and other instant messaging clients such as the excellent Trillian you can sign-on with multiple user accounts, Skype has never been able to do this, limiting you to one username at a time. Here’s a useful hack I came across here that gets past this limitation if you are running Windows XP Pro.
1. Have two admin-level user accounts on your machine e.g. “user1″ & “user2″
2. Have two Skype accounts e.g. “skypename1″ & “skypename2″
3. Login as user1 and create two shortcuts to the Skype application. Name the icons “skypename1″ & “skypename2″ to remember which is which.
4. Open up the first shortcut as you would do normally and sign-on with “skypename1″. Click the box saying “Sign me in when Skype starts”.
5. Right-click on the second shortcut, and choose “run as” from the contextual menu.
6. When the “Which user account do you want to use to run this program” window pops up, click the 2nd button labelled “the following user” and beneath it select user acount “user2″ and enter the password of that account.
7. A second instance of Skype will open up. Sign-on with “skypename2″ and click the box saying “Sign me in when Skype starts”.
8. Now, all you have to do to run Skype with either or both skype accounts is to click the appropriate shortcut(s).
Note: Doing the same on Mac OS X is a bit more difficult, but there is a solution – see this thread in the Skype forums.
UPDATE 02/07/08: There is now an easier and cleaner way to do this – see this newer post