Twidroyd for Twitter
If you use Twitter and have a smartphone, there is no excuse for not using a Twitter client app. For Android phone users, Twidroyd for Twitter (formerly known as Twidroid, a name no doubt changed for legal reasons) stands tall above the rest of the competition.
The amount of extra features in Twidroyd is overwhelming at first. Simply put, everything you can do on the Twitter Website is available here. Of course, it is primarily used to view your friends' tweets and add your own, but if you want to read the trending topics, or search for other topics or people, Twidroyd has you covered. You can view individual accounts and follow them just using the app. You can also edit your own profile as well as integrate Twitpic or some other photo-sharing Website. Similarly, you can integrate your favorite URL-shortening service like bit.ly from the settings as well. This is one of those apps where the designers really do seem to have thought of everything.
Great features aren't so useful if they don't work that well in practice. Happily, Twidroyd functions pretty smoothly. Early on, the application was sluggish, and it was a struggle to refresh the screen for updated tweets, but with each subsequent update, the problem has become less and less noticeable. Getting updated tweets also used to require manually refreshing the app. Now, if you close and reopen it, it will automatically update tweets--although it can be inconsistent every once in awhile. Finally, sometimes errors will occur when trying to submit tweets; but to be fair, that may have more to do with Twitter's servers being overloaded than with the app.
Those minor quibbles aside, Twidroyd is a nearly perfect app. Hopefully, in the near future we'll see a feature notifying users when updated tweets are available, as on the Twitter Website itself. Aside from that, what you can do using the app is almost identical to the Website.