I do review every book I read-now. It all started long long time ago (more than a year ago) when I had this here blog (wasn't really a book blog) and also was a member of LibraryThing's Early Reviewer's program. Back then I only wrote reviews for books I was selected for through the program and posted a few on my blog as well eventually. And then once I decided to join the book blogging community I started posting reviews for all the books I read. If you look at my Read In 2008 sidebar thingy you'll see a lot of the beginning ones don't have reviews. So yes, I review all books I read all the way through currently.
I usually write my reviews on the weekends and post one Sunday and maybe Monday if I have another one. I do it then because that's when I have the most time. I'm sure sometimes I forget things I wanted to talk about in my reviews- I need to start making notes.
Right now I post my reviews here, on LibraryThing and Amazon. I was a bit freaked out about posting them on Amazon but I haven't had anything wonky happen over there that I know of. But MAN some of the stories you hear about Amazon.
How about you? What do you review and where do you post it?