I think different people tweet for different reasons. many just stay in their close knit group, where others (like me) branch out. I find local news agency tweets the most usefull (like following the news story in tacoma about the carjacking with kids), and tweetdeck's search capabilities help me stew down to exactly what I am looking for info on (palm pre, or travel to mexico), or wanting to dialogue about (sushi/sake/best coffee in seattle).
Oh, and if you are looking for a really cool forum, try
www.everythingq.com even if you don't have a Q, the people there are really quite awesome and will keep you in stitches.