Seriously. Why does Twitter makes it SO HARD to find this widget on their site?!?
Because Twitter calls it a "Badge" when everyone else in the world calls it a "Widget."
Whateva.
Anyway, if you have a blog where you can insert sidebar widgets (MySpace, Vox, Movable Type, WordPress, TypePad), then you can use this to show your readers what you are doing on Twitter.
Start here, and then follow the directions - easy as cookie dough! It looks like this, you can adjust the thickness and tall-ness. :)
Other such widgets can be found here.
If you'd like to have your Blog posts be sent to Twitter (like I do), use Twitterfeed.
You can also go the other way, and have all your Twitters sent to your blog (like Kymmie does). For that you'd use LoudTwitter. I don't recommend doing both, then you get caught in an endless loop.
Also, I really like "Snitter" - a windows desktop program that follows your Twitters. More can be found here.
And for Firefox I am switching between Twitbin and Tweetbar. Love how it sits in the sidebar.
Oh yeah, if you want to follow me on Twitter, just go here: http://twitter.com/DarrenTooCool