Personally, i have never been overly interested in blogging, though, you could definetely write your own software pretty easily. The whole concept is extremely simple. Just a basic database insert/edit/delete.
Originally posted by fredmv WordPress and TextPattern are both reasonably popular and free. I've heard quite a few good things about both.
I think it's just a matter of time, but WP is going to become the best blogging tool, if it isn't already and many would say it is. There's just too many well known web design/developers jumping on the bandwagon for it not to be a major player. Being free and letting people tweak the code helps. Blogger will probably always be bigger just based on number of users, but WP is for anybody wanting to do serious blogging. Case in point, former MT users mention it is easier to install and convert a MT blog over to WP than it is to upgrade from one version of MT to the next.