SplitTweet at http://splitweet.com is a great tool if you have a number of accounts on Twitter. Rather than switching between them from time to time in order to Tweet, you can set an account up her for free and bring all of your accounts under the one roof.
Splitweet will display the Twitter feed from all your accounts at once, or you can turn individual accounts off and on. When actually tweeting, you can pick an account to tweet to, or you can do a broadcast message across all your accounts at once.
Some very flash technology this and very useful for handling multiple accounts

Friendfeed at http://www.friendfeed.com is an automating tool you can use in conjunction with Twitter. Friendfeed is a bit of a hub if you like where you can set up links to all your other accounts. Friendfeed collects information from those accounts and publishes it in your Friendfeed feed.
Although Friendfeed is a topic almost in itself, I mention it here particularly because of it's ability to link your Twitter and Facebook accounts among others. If you have a Facebook account and you link it and your Twitter accounts in Friendfeed, then what will happen is that all your posts in Twitter will be posted on your wall at Facebook. It means you are running two social media accounts via one and saves you time

Twitdom at http://twitdom.com would have to be the greatest site relating to Twitter. It is a repository for all Twitter related applications and it is just absolutely amazing what there is in there.
At the time of writing, Twitdom had nearly 500 Twitter related applications in its database. Quite amazing when you think about it that there has been so many third party applications written and is a pretty powerful indication as to the value of Twitter. It also indicates the confidence of the market in that Twitter will become very much the mainstream.

Image via CrunchBase

Your Twitter Karma at http://dossy.org/twitter/karma/ is a really useful site for having a look at your followers and who you are following. It's great for managing your account from a followers/following perspective.
Unfortunately it doesn't seem to load a fair few times and can be unreliable, but when it is working it's great. It shows you all you all the people you are following and all those that are following you. Underneath each avatar it tells you if you are following them and if they are following you. You can also sort by people that you are following who aren't following you back. This is great for management as you can decide whether or not to unfollow them.
By checking the boxes, you can actually do a bulk unfollow of a heap of people at once as opposed to going to every individual Twitter account and clicking on “unfollow”.
You can also list those that might only be following you and decide if you want to follow them back. Again, this can be done in a bulk manner

Twitter is absolutely fantastic application whether you use it for business or pleasure.
I hope the tips and resources in this report will make it a fantastic experience for you.