There are multiple ways to use Twitter, and if you usually use the Firefox browser, Power Twitter is an add-on that adds some interesting features.
Once installed, the Twitter home page will essentially load twice. This adds a fraction of time, but it's not prohibitive. Immediately, there are three buttons above the 'What are you doing?' box - Post photo, Shorten link and Today's question. The first two are really useful, and you can choose which photo site to utilize. The shorten link gives you a few extra characters to tweet with.
Today's Question is a silly option, but if you're really desperate for something to tweet, you can always use that to answer. Much better is that all the shortened links in your Twitter feed are expanded, so you can see exactly what they contain. It also adds a re-tweet RT tab to each tweet, which is currently missing from the normal Twitter page.
While all this is useful, it comes at a price, which is an advert added to the sidebar. It's not too intrusive, but noticeable. Overall, while the functions are useful they do make the minimal Twitter design a bit more cluttered. If you're not too bothered about that, you may find it a really useful tool.
Power Twitter really does make the Twitter home page more useful!
