I've tried precisely three of them and have not been able to get up enough urge to keep playing. The Heroes of Might and Magic game might have been okay if you could do more than like, two things a day, or whatever, but it still would have been HMM lite. The Dungeons & Dragons game was pretty disappointing. Finally, Jeopardy is okay, I guess, but again, you can only play two games a day, and it certainly doesn't capture watching the show or playing a real full-fledged video game version of Jeopardy.
For online browser-based gaming I'd rather play
Jagged Alliance Online, or the upcoming
Shadowrun Online, and ignore Facebook's crap. If you have Words with Friends on your phone or whatever it would probably be a better use of your free time.