If you're interested in monitoring twitter on a constant basis, but need to keep your eyes on the prize - the tutorial by Amanda Ghassaei will be of interest. Amanda describes how to create a device based on an Ethernet-enabled Arduino that will search for tweets based on certain parameters and have them read to you by a digital text to speech system. The system uses Speakjet and text-to-speech ICs, which is a lot simpler than expected and works well. Sound output is via a simple audio amplifier based around an LM386.
Apart from the usual instructions Amanda also documents the instructions for the Speakjet and text-to-speech ICs so almost anyone could get this project talking. Even if you're not interesting in talking tweets, adding speech to other projects can be possible. So visit Amanda's project page for more information. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
... or for more program space, I/O ports consider the Freetronics EtherMega - the Arduino Mega2560-compatible with onboard Ethernet, microSD socket and optional PoE: