FeedTwit is a twitter app that can send your twitter @ replies to you as a text message. 

Typically, when you pair your cell phone with Twitter, you have to designate who's feeds you want to receive as text messages. If someone mentions you but you haven't told twitter you want their text messages, then you won't receive notification. This is the gap that FeedTwit fills.

Additionally, FeedTwit can take an RSS feed and send it to you as a direct message. With this capability there are many different ways you can use FeedTwit besides getting your Twitter mentions.

To use this app you don't have to download anything on your phone, you just follow @FeedTwit to receive a password and then follow the directions. This means you can use FeedTwit on any phone that supports text messages and don't need to invest in a data plan to keep up with Twitter.