I watch Whose Line reruns all the time. It is possibly my wife's favortie show. It is always good for a bunch of laughs. As Todd Z said we watch it on ABC family. Also the British version is on all the time as well on BBC.
How about that new show do out next week, "Thank God You Are Here" that looks like it will be kind of similar I planned to check it out.
Also not similar but equally funny or maybe even funier is the show on the Canadian chanels that is like our candid camera only they go way farther. I forget the name, Just Laughs or something like that. They pull some wicked things on unsuspecting people, the gay cops one comes to mind, that one was hilarious, or the nun with the porn. Some of our Canadian folks will know what Im talking about.