The only one I can think of that's decent without a downloaded launcher is LordCraft, I haven't played it myself but my brother enjoys it.
Chat with our AI personalities
just google free checkers game online
You can play Family Fued online at www.games.com, which is the AOL games site. It's under 'word games' and can be ususally found on the front page.
You can find a huge variety of online games in various categories at Addicting Games dot com. No registration or downloading is required and all games are free..
The fact is that when new games come out they will obviously have to be downloaded to play but then there comes a way improved game of it and then the first one will eventually become free and online.
There is currently no way to legally play minecraft without downloading it or purchasing it from a store. Borrowing a friends copy or account may be the best solution if you do not have money to purchase it yourself.