The best free open source software for Mac OS X
If you live and work on a Mac, you'll want to try these 10 killer open source apps -- InfoWorld's top picksFollow @peterwayner
Handle feeds wisely with RSSOwl
There are a number of good commercial RSS feed readers and some good free ones, but some of the good free ones aren't open source. (NewsFire, Shrook, and NetNewsWire are just a few.) RSSOwl is a cross-platform tool built out of Java, Lucene, and the Eclipse Rich Content Platform. It doesn't set up its own open source ecology; it's part of a bigger one. You can add new menu items, new views, or preferences pages just as you would to any other version of Eclipse. The UI is very configurable.
RSSOwl also has more extension points inside. You can override all of the handlers for each XML element, the particular formats like RSS or Atom, or the protocol. This can be useful because some RSS feeds require formats that are far from standard. Some sites insert custom images and other bits of data that might be handy.
One of the RSS feeds from my site Flyzone.com, for instance, includes images with a real hack because many RSS readers can't handle the extra img tags. Adding a bit of code makes it possible to take apart these special instances of RSS.
RSSOwl juggles multiple RSS feeds, stores the results locally, and allows you to search them using Lucene.
Set your e-mail free with Thunderbird
The Mozilla foundation spends the ad revenue checks it receives from Google on more than Firefox. Thunderbird is a mail reader that is open source in two ways, just like its browser cousin. First, the code itself is available under the Mozilla license. Second, the developers have built the same sort of add-on mechanism for Thunderbird as they created for Firefox.
There's a wide range of plug-in applications available for Thunderbird. Leet Key will translate your e-mail into either L337 speak, ROT13, or several other useful formats. Russ Key takes Russian words typed phonetically with a roman alphabet keyboard and translates them into proper Cyrillic. Enigmail handles all of the OpenPGP encryption so that you can scramble your communications.
Thunderbird add-ons let you extend the mail client for both fun and profit. One called Enigmail allows you to exchange encrypted messages.