I probably started tweeting a bit earlier but the bulk of my tweets were in 2010. Here is a tag cloud of those tweets:
Nice to see that retweet (RT) was one of the largest. That is one thing nice about Twitter. It does not take a lot of effort to share information and knowledge.
Meta
I used an open source python program to dump all my tweets into an sqlite database (for further analysis), wrote a small python program to read the db and dump to a text file and use Wordle to generate the tagcloud.