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.
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!
Marathon is a GUI test tool that allows you to play and record scripts against a Java Swing UI. It's written in Java, and uses Python and Ruby as its scripting language (the emphasis being on an extremely simple, readable syntax that customers/testers/analysts feel comfortable with). Marathon includes a recorder, editor, player, and debugger to simplify working with test scripts.
iCal is an elegant personal calendar application that lets you keep track of your appointments and events with multiple calendars featuring at-a-glance views of upcoming activities by day, week or month. iCal lets you create separate color-coded calendars for your home, school and work schedules, and it lets you view all your different calendars at the same time from within a single unified window. You can use iCal to remind you of time commitments, keep track of your deadlines, send and receive email and text-message notifications, set alarms, and even create and prioritize To Do lists.
iSync is Apple's new device-synchronization software that automatically synchronizes your contact and calendar information between your Mac, your cell phone, your PDA, your iPod, and your Mac OS X Address Book. iSync also resolves synchronization conflicts no matter how many different digital devices you use. It synchronizes your data in both directions and uses the most current information. If you’ve made a number of changes and the change is unclear, iSync will ask you which information to use when you sync.
iConquer is an addictive game of world conquest, played by 1 to 6 players. The object of the game is to conquer the world by occupying all 42 countries on the map. It features artificial intelligence algorithms to set the player up against formidable computer opponents with six AI "personalities" to choose from. It also supports network play, a powerful help system with detailed information on each stage of the game along with tips and strategies, customizable strategy play, and gorgeous graphics.