miniSynth (iOS) app for $0.99

The original iPhone synthesizer is now in its 2.4, just happily out of college. With a tasteful set of tweaks here and there, including its shiny new slide-friendly keyboard, and platform-first ZERO LATENCY, it's here to muse and amuse. It retains both its original skin, and the battered '52-Tele one, switchable via Settings. Complete with a recording and playback module, an audio file browser and ability to export via Wi-Fi.