You have several options for running more than one blog. I'm not that familiar with Movable Type - the sofware behind typepad.com blogging services, but most (if not all) blogging software will let you run your blog either in a subdomain or in a subfolder of your domain.
For example, you could run blogs like:
If you're running free blogging software like WordPress, you can either have separate installations of WordPress for each blog or run a single WordPress Mu installation and have "infinitely many" blogs until your server grinds to a halt, everyone here complains until they're moved off the server, and people start dying!
Let us know if you think you're going to continue to use Movable Type or if you're going to transition to WordPress and we can give you some more detail!
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