It is amazing how many people tell me they could never have a blog, and then later tell me ideas for their non blog that they could never have. I work with a great guy who tells me a new idea for his non blog every day.
Everyone has at least one good blog in 'em. (I have 2 and possibly more on the way).
Here's a blog with a solid theme: a couple is getting married this year, and has substituted wedding cake with cupcakes, the baking of which will be done by a friend. (I may or may not know these people. I can never remember what I'm allowed to reveal. Identities are probably revealed in the text.)
The blog is all about the making of the cupcakes. Recipes, experiments, etc. For the right audience, it is a very good niche with a loyal fan base. Check it out!
ps. Sadly, there is no blog about the actual wedding! Hello?! People, what are your hopes? your dreams?