Power Twitter is an add-on for Firefox that takes regular Twitter and gives it mag wheels, a spoiler and a brand new engine. 

After installing Power Twitter and restarting your browser, your Twitter page will have these new features:

1) inline embedded media from Flickr, YouTube, TwitPic and others
2) expanded URLs so you can see where links might take you
3) twitter search and search results right on the page
4) peek – an avatar mouseover that lets you see recent tweets from that person
5) status updates that are happening with your friends on Facebook
6) when possible additional web updates (Flickr, blogs, etc.) for certain users

Power Twitter is yet another great free contribution to the Twitter community from very talented developers.

Find out more about it at http://83degrees.com/post/Adding_Features_with_Power_Twitter

TwittyTunes is a browser extension for Firefox and IE that lets you easily Tweet whatever you are listening to at the time.

In addition, you can also Tweet the websites you visit, and the videos you watch.

To be able to Tweet the songs you are listening to, you’ll need to have FoxyTunes installed.

Otherwise, you can still post about websites, videos, and general updates. Take a look, and listen, to TwittyTunes at http://www.foxytunes.com/twittytunes/

The folks over at honkiat.com took the time to assemble a collection of over 100 highly attractive Twitter icons of all styles, shapes and sizes.

These graphics are all free of charge, so you can head there and be sure to find something that suits your needs.

My personal favorite is the Twitter bird in the hard hat. Nice!

Browse the 100+ graphics here: http://www.hongkiat.com/blog/100-remarkably-beautiful-twitter-icons-and-buttons/

Tweeterized is a free, dynamic Twitter signature creation service. Just insert your username and you will be supplied with code that you can use in forums, websites, myspace profiles and so on.

These signatures will be kept up to date with your latest Tweets, and will allow people to follow you by clicking on your sig.

Tweeterized comes in two sizes and six colors.

Visit Tweeterized at http://www.tweeterized.com/

Twitter Image is a custom Twitter background design service for professionals. These backgrounds are designed not only to look great, but to add to your business as well.

The quality of the designs is obvious when you visit the Custom Backgrounds gallery.

If you want to go for a top level design for your Twitter background, this is one place to check out for sure.

For those not in business, they also have a fairly large collection of free backgrounds that you can grab and use.

Visit Twitter Image at: http://www.twitterimage.com/

Blackbird is a client that brings the world of Twitter to your Blackberry.

Blackbird is a compact, simple application that lets you keep track of your friends and your updates.

The application is free to use.

Grab it at http://dossy.org/twitter/blackbird/

TweetGrid is for Twitter users who want to process a lot of information very quickly. It lets you search up to 9 different topics, events, converstations, hashtags, phrases, people, groups, etc without refreshing. The information comes through in real time, letting you keep your fingers on the Twitter pulse.

You can create your own layout with TweetGrid, and at any time you can pause the searches you are currently running. 

TweetGrid supports pretty much every browser, except for IE6. You can also setup new grids and then share them with other people.

TweetGrid is free to use, and easy to setup.

Check it out at http://tweetgrid.com/

GPS Twit is a nifty application for the iPhone that makes it easy for your friends to find you. No more wandering around wondering where on earth Jimmy got to!

GPS Twit answers the question. Where are you and what are you doing?

Visit the GPS Twit webpage at http://gpstwit.com/

twit.pix.ly is an interesting new take on the world of Twitter. In an ongoing “Twitter Avatar Combat” battle, different avatars are pitted against each other to find out who reigns supreme.

Winners of battles are decided by vote, and only people that follow you can vote for you. Users that want to vote for more competitors can do so by following more people.

Take a look at Twitter Avatar Combat at http://twit.pix.ly/

TwitterBacks is a cool and (awesomely) free twitter backgrounds site. A guy by the name of Jim Kukral created a series of twitter backgrounds, and gave them away, including the PSDs.

So, you can grab the backgrounds and use them as they are, or you can take the PSDs and use them as a base. This saves you all the time and trouble of figuring out what should go where.

The other element he has to offer is that once you’ve created a new background from one of the PSDs, if you upload it to Flickr and tag it with ”twitterbacks”, it will show up in the Flickr feed on the TwitterBacks website. Everyone likes extra attention for their Twitter Page.

Visit TwitterBacks at http://www.twitterbacks.com/