I chanced onto this website a while ago, and I want to share it, for several reasons.
1) It is free. And I mean this in all sense of the word, because sometimes I type "free printable worksheets" into Google and I still get sites that ask me to register. Excuse me, but that is not "free". (I'm controlling myself from going off on a principled rant here.) (FYI: there are no worksheets on this website; that was just an example.)
No registration. No password. And the site is .org, which is in itself a huge plus.
2) It's well-organized. Nice lists. (You might be surprised at how few ESL websites are clearly organized.)
3) It has lots of online vocabulary games, from beginner-level to more advanced. It also has listening/reading activities for upper-level students. I don't like all of the games, but there are lots to choose from.
Here it iis: www.manythings.org
I told all of my students that I would like them to try it out over summer vacation; since I know some moms (with good reason) freak out at the mention of "computer games", I typed up a little note for the students to take home and urged them to look at the site with their moms. I also had students from several classes do the games online at school during break times.