1. Just Tweet It! This is a Twitter Directory Tool. You can use this to search by Categories.
2. Twit Scoop Search trends, find out what's buzzing on Twitter in real-time!
3. TwiStori Discover what Tweeter "wish", "feel", "believe", "think", "hate", or "love". Just click on one of the keywords listed on the left, and current tweets containing the chosen keyword. (Takes a little bit to load)
4. Tweet Volume for Keywords Type in keywords or phrases and see a chart of how often a particular keyword is used. You can even click on "Past Day", "Past week" or "Past year" to see the keyword results for your search.
5. Twitter Moniter This one monitors in real-time, based on your keyword or phrase search to see what's being tweeted, how often, at what times, and by whom.
6. TimeLine of Tags This one will show a graph timeline based on whatever word you type into the search box, and show you when and what time the word or tag is tweeted the most or the least. Gives a time line. If you hold your cursor over the graph, it will tell you the times of day/night the keyword is being using/was used.
7. Tweep Search Search for Friends & Followers by username, or keyword search bio index.
8. Twitter Search Just type in a keyword and find all the twitters for a particular category or niche. You can also follow them from this page and it is a live feed, so you get reulats in real-time.
9. Twellow Like the yellow pages for Twitter. You can do indepth search for any category, hobby, interest etc. You can even type in a keyword and search only among your followers to find similar interests as you.
10. Lazy Tweet This one you can use to post questions and find answers. Kindof like a Twitter club Q/A.
