Originally I didn't expect to have much here, but that eventually changed. More and more shows are premiering on digital platforms like Amazon Video, CW Seed, Geek & Sundry, Hulu, Yahoo! Screen, YouTube, etc. And of course there are some shows that have their own website, or that stream on other sites I may not be aware of. There are shows I'd like to watch on sites like Amazon Prime or Hulu Plus, which would require subscriptions that I can't currently afford, but maybe someday I will. Meanwhile, there are plenty of shows to be watched online for free. Of course, there are also lots of shows I watch on sites like Hulu, that originate on TV. Obviously those aren't web series, but there are also some shows that I do consider web series, that some might consider TV shows (in large part because many people can stream web shows on their TVs, which is something I've never done... but even if I ever did, I'd still consider them web shows). It gets more complicated when you talk about services like Netflix (which I don't currently have). Since I doubt I'd ever watch Netflix original series on my computer, just TV, if I ever subscribed to the service, I'd call those TV shows... but there are people who consider Netflix and Hulu, and possibly Amazon Video and other services, to be essentially the same format. I disagree. For me, there's still a line between web and TV, but the line does get blurrier all the time. (There are also some shows that may air online in the U.S. but on TV in other countries. I do my best to figure out where a show aired first, so I can decide whether to call it a TV series or a web series, but still... blurry lines.)
Perhaps the blurriest line of all comes in the form of shows that start out on TV, but later get cancelled by their network (or simply removed from a network's TV lineup, which isn't necessarily the same as being cancelled, these days), and move online for new seasons. Thus far I have little experience with this phenomenon, but it happened to The Legend of Korra in the middle of its third season (though it sort of remained a Nickelodeon show even when it was no longer airing on Nick). And when NBC cancelled Community after its fifth season, it got picked up for a sixth season by Yahoo Screen. (For now I won't bother linking to those shows on the web series navframe, but I might do so someday, especially if this happens with more shows I watch.)
You could find plenty of other webseries that I've never seen but that you might like on some of the websites listed on my online video links page, as well as on Wikipedia's List of web television series. For more personal suggestions (by people other than me), check out the Web Series thread on Geek & Sundry.
As for websites that are not about watching shows, there aren't many I'm ever going to feel the need to review. There are a couple listed here, though. For some more of my favorite sites, you might check out tek's preferred links.