I have a pet peeve.... Blogs with dark backgrounds are incredibly difficult to read. If you are writing a blog, please consider changing your template to one with a light background. Here are some reasons it makes sense.
1. Some of us still have crappy old computer screens and can't read your blog because the contract is screwed up.
2. Some people are color-blind. I am not, but keep that in mind when choosing a design for your blog.
3. Reading light writing on really dark backgrounds can give some people headaches, make them have to squint and in general, they will just click off and not read what you have to say.
Other problems I see with people's blogs are that they need help with html. If you post on the template sidebar and everything goes off format, the post is probably too wide. Find the width and decrease it until it all fits again.
Moving stuff (ads in particular) on the front page is irritating. Try to not put too many irritations on the front page (I know I broke this, but Helen Ready's coming down soon...)
Keep things organized as much as possible.
This was sparked because I really wanted to read someone's blog and just flat out couldn't. I'm sure I could think of a few more things that bug me when trying to read your blogs and I'm sure a few people could rip mine apart also, but I'm done b*tching now... The frustrated rant is now over LOL!