I've been watching anime fansubs for almost a decade now. I've been watchin since there weren't very many of them, since I could actually have downloaded all fansubs ever released in English within a month if I really tried to (though maybe not with the Internet connection I had back then), and since then things have escalated rapidly. Back then there was no YouTube, there were no other video streaming sites, and nobody wanted to waste bandwidth hosting their own videos so watching the episode online was simply not an alternative.
Now all fansubs are streamed online on a multitude of platforms. There are sites dedicated solely to streaming anime and countless groups or fans uploading video files to the available video communities, from which they often get deleted quickly. The FLV format allows files to be drastically reduced in size and hosted on private servers, and there are services to upload files to multiple video-hosting services at the same time, making the effort it takes to delete files larger than it takes to upload them. I should point out though that licensed anime is what the distributing companies put an effort in deleting, the Japanese have never seemed to be very bothered with their series being fansubbed. Until the series is licensed in another country it only increases their potential market, making the series available to a larger selection of the world populace. And who doesn't want fans anyway?
Apart from streaming there have been countless other changes (improvements most people say). There are file-hosting sites used to upload and download fansubs as well as the traditional torrents, FTP servers or IRC bots. Maybe not so much public FTP any longer. The amount of fansubbers has increased too, scaling to catch up with the amount of shows available. All new popular anime shows are subbed, all of them, and the only thing that bothers me is that so many fansubbing groups sub the same series. The big shows, like Naruto, Bleach & One Piece, are currently subbed in English by at least ten groups each. The differences between the releases aren't so big.
Some use MP4, some MKV. Some don't have Karaoke, some do. Some manage to translate foreign jokes, others don't. Some fall behind on their releases, but keep going anyway. Some of them should just focus on something else and let the ones that are doing the job well have all the work. Or they could collaborate, combine their efforts and make the best subs out there. Why does everybody want a group of their own? I remember way back when when everybody subbing something actually did a good job. It wasn't about having their own fansubbing group, it was about making the shows available to the masses, by the fans for the fans. It was an honorable occupation.
But if you're reading this you probably knew all this already. :)