I follow a number of Twilight related blogs. There are tons of fabulous blogs out there. I'm only mentioning a few.
Twilight Lexicon: This is THE Twilight blog. It's loaded with original content including numerous links with personal correspondence with Stephenie Meyer. It's uploaded frequently and very user friendly. I like that they have full RSS feeds, which makes it easy to follow through Google Reader.
Twilight Novel Novice: A fan site started by a middle school teacher. It encourages teens to read all kinds of books and recently spawned an affiliate book site called Novel Novice. They also feature a lot of downloads - wallpapers, fan art, and fan fiction. They host fan fiction contests that highlights some of the best fan fiction anywhere on the Internet. This is my second favorite blog to Twilight Lexicon. The blog is updated frequently with different posts than many other sites offer. The blog has a sister site that features all kinds of YA books: Novel Novice. I highly recommend both sites.
Twilight Moms: A great site for older Twilight fans. The blog is updated frequently but doesn't have as much original content. It also has a cut RSS feed; I hate being forced to open a site instead of reading from Google Reader. The real draw to Twilight Moms are the forums. They have forums on the movies, books, and in depth character discussions. To join the forums you have to be 25 years old or a mom or be married. Twilight Moms also has a great sister site called Eve's Fan Garden that features YA books and great author chats.
Twilight Source: I actually don't follow Twilight Source's blog. I don't think it's that different than the other sites out there. But I do like their website. You can customize the theme of the site to be Team Edward, Team Jacob, or Team Switzerland. They have fun lists, fan art, forums, and downloads. I recommend Twilight Source largely because of their podcast, Imprint. I'm a regular listener of Imprint and think it's the best Twilight podcast out there.
Still Wandering: This is a really interesting blog. It's by a Film PhD student. She was in the right place at the right time and got to view several days of filming of the first Twilight. Since then, she's been involved in premieres and Twilight conventions. She has great insight into the movie process. Here's her Twilight filming posts: http://imstillwandering.blogspot.com/search/label/twilight%20film%20set
Robsessed Pattinson: My fluff blog. For obvious reasons. It is far from the only Rob blog out there but it's the one I got into the habit of reading. The comments get pretty hot and heavy at times so I generally don't read those. As much as I drool over Rob, I can't understand how someone can have such detailed fantasies over a person they've never met. But that's just me. Regardless, there are lots of good pictures and videos on the website and it's frequently updated.