I'd like to mention my views on a newer site
http://www.pokerwit.com
Pokerwit is not necessarily a training site if you go by the traditional definition of training sites. It's a site which has a unique way of dealing with hand histories, which I believe is really effective in understanding hands. Each hand is played by the community, so a user gets a statistical perspective of how most people would play that hand. The people who have played the hand explain their reasoning for their play on every street, and in the end, people discuss why the lines were optimal or not. I feel this site has made me view hands in a much more structured manner, than normal, and I think a lot of you would notice it too.
They've recently introduced a new PRO Section. In this section a ton of reputed and highly successful online MTT pros discuss hands they've played in most of the HSMTTs as well as other mid stake MTTs, and their quality of explanation is unparalleled. It's unbelievable how much thinking goes through every hand, even though a lot of them play ~ 20 tables or so at the same time. This section is definitely a welcome addition to the website, and for 5$ a month, it's an absolute steal. The pro discussion after every hand is also excellent, since it's a bunch of regs who discuss how they would have played that hand, and for a learning player, one can't ask for more.
People who are really looking to improve their MTT game, should definitely give this a try. Once you check out their free hand section(which is a huge database in itself), I assure you, you'll want to check out the pro section, primarily due to the quality of players and their analysis there.