py-xmlrpc is an extremely fast implementation of the xmlrpc spec for Python (written in C). It supports both blocking and non-blocking clients and servers on Windows and POSIX platforms. Version 0.8.1 is 100% compliant with the xmlrpc validator found at http://validator.xmlrpc.com.
Snak is a full-featured IRC client for Mac. It features a configurable window view, an inbuilt address book, logging functions, multiple connections and multiple channels per connection, a find function for text within channel listings and channel text, as well as scripting capability, amongst others.
ObjectDB for Java/JDO is a powerful yet compact Java Data Objects (JDO) Object Database (ODBMS), written entirely in Java, and compliant with the Java Data Objects (JDO) standard developed by Sun (JSR12). ObjectDB for Java/JDO is designed to efficiently handle databases of various sizes, ranging from a few KBs to hundreds of GBs. Among its features are small footprint, high performance, rapid development, easy deployment, and flexible architecture (1-Tier, 2-Tier, or N-Tier).
LaunchBar provides lightning fast access to thousands of files, Web bookmarks, email addresses, and applications just by entering short abbreviations. The set of items and their corresponding abbreviations don't need to be configured manually, as a powerful, adaptive abbreviation search algorithm is used to index any thinkable abbreviation of the item. A system-wide hotkey makes LaunchBar easily accessible across the whole platform.
Liferay is an enterprise portal. It handles users and portlet drawing, has a full administrative interface, supports all the major databases and the main J2EE application servers, and has single sign-on capabilities and multiple language support. It uses Apache Lucene for document searching. A number of portlets are included, including a guestbook, a calendar, a mapping utility which uses Expedia, news, polls, a document library, and live stock information.
Openline is the open source version of Hotline. Hotline is a PC/MAC client/server application that provides users the ability to create and manage a desktop community. The application has file uploading and downloading, instant messaging, a bulletin board, threaded news, and public and private chat.
MidiKeys is a little application that displays a piano keyboard onscreen. You can click the keyboard or use the computer keyboard to play MIDI notes. The keyboard window can be made to float on top of other applications and supports transparency. Also, MidiKeys will optionally set up hotkeys for the computer keyboard so you can play notes in other applications (such as a sequencer) without having to switch back to MidiKeys. It works great on a PowerBook!
SynthTest is a somewhat simple application for OS X that allows you to pick a MIDI source, a MusicDevice AudioUnit, and an Effect or MusicEffect AudioUnit to play with. You can open an edit window for both the synth and effect. If they do not have a custom edit GUI, the generic editor view will be used. SynthTest has a reference implementation of preset support for Audio Units. It is primarily intended to be used by Audio Unit developers for testing purposes (the source is available), although it can be great fun to play with all by itself. It is complete enough to be used for live performances.