• Use the @ followed by someone’s name to aim a comment at someone specific.
• Direct Message – click on the “direct messages” to see the private personal messages people have sent to you, or send a private personal message to someone else. If your phone is enabled, you will get these on your phone.
• Use the # followed by a term, if you want to follow a “trend” other people are also talking about, such as #h1n1. This makes topics easy to follow.
• Enable your phone. This is one of the “truly useful” ways I have used Twitter. Send a text message to 40404 and it will appear in your Twitter stream. I have used this feature to meet up with people for dinner, and to get prayer requests. When I don’t know someone’s cel phone number, they can still contact me this way without a computer. Of course, getting someone’s cel phone number works even better, but this can be useful.

Some interesting folks/services on Twitter:

• CDCEmergency - Exactly what it sounds like, the Center for Disease Control.
• MarsPhoenix – No more data is coming back now, but this little lander was the toast of Twitter for awhile.
• Astro Mike – Perhaps you heard this was a “fake account” but it’s still NASA news goodness.
• BoingBoing - Interesting stuff from around the web
• Make – DIY projects, plans, and niftiness.
• Woot – a new deal every day (I have purchased some of these products, they’re great)
• Spymaster – a Twitter-based game where you can assassinate other players
• San Francisco - That’s right, the CITY of San Francisco is on Twitter. And it listens to complaints.
• Celebrities – I am not going to list them here because I would not catch them all. Also, they aren’t always the real thing! You think you are following the Dalai Lama? Think again!

Ok you have a few followers – now what? Well there are a lot of “fun” (or perhaps “silly”) things you can do to track your Twitter popularity and things like that. Here are the ones I like best.

• Twanalyst - this shows you your “Twitter personality” and gives suggestions on how to round it out.
• Grader – this compares your popularity with others
• Twinfluence – this compares your popularity, but using some different and interesting stats
• Twendz – This is especially great if you have a business, because it lets you track Tweets that contain your name or keyword, and makes a graph of the negative or positive sentiment in the tracked tweets.

And more services are popping up all the time, like:

• CheapTweet – this site keeps you informed of coupons/deals.
• Twellow and WeFollow are both “Twitter Yellow Page Directories”.

I’m sure that more has come out in the time it took me to write this article. Feel free to post your favorites in the Comments. I get a lot of my information on new features from TechCrunch. As a final note: if you want to use friendly (though comparatively little-used) “Twitter-like” service without the hype, try identi.ca.  You won’t find Paris Hilton on it, but I wanted to point out there ARE many Twitter alternatives.