Dress up your Tweets with Twitterkeys
Adding symbols to Tweets used to involve remembering a whole bunch of keystroke combinations but thanks to TwitterKeys, created by the folks at The Next Web Blog, all you have to do now is cut and paste.
Just drag the TwitterKeys bookmarklet to your toolbar and next time you're looking for a symbol, just click the link to open the directory. Find the symbol you like, copy it (Control + C), then paste it (Control + V) into your Tweet. Pretty sweet.
Two things to note: TweetDeck users will need to change the apps defult font setting to international/utf8 in order to use TweetKeys. Also, Mac users will recognize many of these symbols from the Special Characters set found on OS X. While not all of those characters will work cleanly in Twitter, the ones selected for TwitterKeys will.