1. Find people to follow: Twellow | Tweepsearch | Tweepz | TwitDir | WeFollow | CelebrityTweet | Twitterholic or just search #ff in Twitter Search.
2. Find journalists, news orgs on Twitter: MediaOnTwitter | Muckrack | News “papers” on Twitter | List of Malaysian media | List of Malaysian journalists
3. Find those tweeting at specific location and specific subject matter: Nearbytweets | Twitterfall
4. Shorten links before posting: Bit.ly | TinyUrl
Both offer customization of links to something more memorable and Bit.ly also offers stats so you can see how many clicks you are getting from your short link. Just add the plus(+) at the end of a link eg: http://bit.ly/xxxxx+ to find out more.
5. Find out whether the story or link you want to tweet is current or popular or has been tweeted already by your followers: Topsy
6. Use popular Twitter clients: UberTwitter, TweetDeck, Seesmic, Echofon, Twitterrific, Tweetie (recently bought by Twitter). An updated Twitstat list of popular clients.
7. Graph your stats: TweetStats
8. Post and share photos: Twitpic | TweetPhoto | PikChur | yFrog | TwitGoo | Picktor
9. Post and share videos: yfrog | TwitVid | Others
10. Journalist tips and guides: Twitter tips for journalists from Steve Buttry | The Journalist’s Guide to Twitter by Leah Betancourt | 6 Twitter tips for journalists by JD Lasica
Bonus: Great complete guide with best practices and case studies for convincing management on Twitter.
(Attribution: From various sources including Mashable)