An addendum to my previous post: there is one drawback to applets, and it is that no-one takes them seriously, even when they are good.
Even the forums of the excellent Freegamer blog lumps them in the category "Proprietary & Web Games" (with the subtitle "Just in case you really have to talk about them... "!?).
Maybe the problem is that there's so many rubbish games out there? Do a simple search, and you'll probably come across a million versions of Sudoku, and applets that were written back in 1995. However, there are plenty of good games out there.
Maybe what the genre needs is something like Freegamer, but dedicated to online games, to sort the wheat from the chaff. Hmmm...