Add Unicode fonts
Text generators like http://graphics.glig.com/generators/unicode_text and http://eder.us/unicode.php add a lot of fun to Twitter. People like @Skrillex make even so much use of it in his tweets that recent Unicode character additions aren't even visible (probably because Android doesn't support some). I would like to be able to type part of my tweets in italics or strikethrough via Seesmic too :)
Interesting suggestion – will investigate more – thanks for your feedback.