In helping someone setup a Thingamablog, I was surprised to count all the free stuff that needed to be added for blogging to take place. Of course, I didn't add them all at once but over time. However, consider this short list of blog peripherals that I consider essential when setting up a new blog to have.
Tools to Track Subscribers
Feedburner.com — Lets you track who's subscribed to your RSS Feeds
FeedBlitz — Allows people to subscribe to email versions of blog entries
Tools to Track Hits or Number of Visitors and Where They Are from
BlogPatrol — Get a hit counter for your blog (tracks unique IP Addresses)
StatCounter — Put this code on every page, and you can find out which of your blog entries are popular by counting the hits, etc.
ClustrMaps — See visitors as red dots on your map of the world
Connecting to Others
Haloscan — Enable commenting on your blog if it lacks that feature
Blogrolling — lets you organize and easily share other blogs you read (this attracts traffic to your blog)
WikiSpaces.com — get your own wiki for free. Tell them you're an educator and they remove all advertising
Gabbly.com — online chat
President, TCEA TEC-SIG
Director, Instructional Technology
San Antonio, Texas