Recently, Ann Handley posted "Everything I Need to Know About Twitter I Learned in J School" which is a very useful discussion of using Twitter from the Journalism perspective. Although I do not disagree with her comments,  I'd like to offer the Technical Communication perspective:
1. Be concise.
You only have 140 characters, so real estate is limited. Make the best use of it by using the right words. Most technical communicators feel they've grasped the art of brevity, but Twitter puts it to the test.
2. KISS - Keep It Simple, Stupid
Simplicity is refining your thoughts to the barest essentials. Mentioning two or more unrelated thoughts in a Tweet is likely to confuse your followers. Confused followers tend to leave. And what's the point of tweeting if no one is listening?
3. Context is king.
Make good use of # hashmarks to indicate the subject. Even though you're limited to 140 characters, you can provide access to external sources which elaborate on the context. Link to articles, blogs, or tweets for further elaboration.
4. Focus on the task.
What do you want your followers to do? Think? Respond? Follow a hyperlink? Consider the ultimate purpose of the tweet and how you can best help your followers achieve that goal.
5. Use active verbs.
Active verbs are shorter and easier to follow than passive verbs or verbal nouns. This may mean breaking grammar rules, but those are more flexible than the 140 character limit.
6. Use relevant graphics.
If you link to a picture, make sure the picture is either the focus of your tweet or somehow elaborates on what you are telling your followers. Leave it out if the relevance is not obvious.
7. Cite sources.
Retweeting is polite and helps your followers know where you got the information. There may be more to it than just a lone tweet and followers can follow-up or just follow the original tweeter. Moreover, the person you retweet will RT you back and you may gain followers from their pool.
8. Know your audience.
The most important part of any communication including Twitter is to know what your followers want to hear. If you can humorously tell them how you ate mashed oats for breakfast and they'll appreciate it, then do so. But if they're following you to hear about politics, news, or fashion, you can leave out the oatmeal tweet.

1. Navigate to www.amazon.com.
2. In the search box, select "MP3 Downloads."
3. Click the "Go" button. Results appear ordered by "Bestselling."
4. Select "Price: Low to High" from the "Sort by" menu. The first several pages you see will be free music.

If you're not sure you'll like a free song, click the play button to the left of the Song Title and listen to a sample. If you're still not sure, download it anyway. You can always get a refund. LOL