I'm a programmer and I've written some software. That's hardly surprising - its what I'm paid to do. What's more interesting is that you can download some of it. Many of my most exciting projects are, sadly, not open source. (This includes my work on Akai MPC software and firmware.)
PGMidi
The canonical iOS and macOS library for MIDI device access (makes CoreMIDI easy)
It's quite old, but still well used.
An example project showing how to use the CoreMIDI APIs on iOS 4.2. Many iOS audio projects have picked up this code to use for their MIDI implementations. Download the code from gitorious here. Read the blog entries here and here.
A Boost framework for iOS (BoostOnIphone)
Creates an easily usable iOS framework for the Boost C++ libraries. Download the source from gitorious here. Read the blog entry here.
Eulagise: Adding a EULA to a Mac DMG
A script that allows you to add a EULA to your DMG so the user has to "accept" before the DMG mounts. Get the code on gitorious here. Read the blog entry here.
UITableView with an "empty view"
Downloadable (older) software
This is the older code, some of which has been online for a very long time, and by now I'm not necessarily proud of it. The problem with pointing to old code on the web is that times move on, and untended code rots. It doesn't change, but it's not kept up to date, and it doesn't reflect how you'd wish it was programmed today. However, people still use these programs, no matter how clumsy they may now be - so I'll leave the links here for your enjoyment.
TSE3 sequencer engine library
A powerful portable C++ MIDI sequencer engine library.
Link: TSE3 page
Anthem Linux MIDI sequencer
KDE based MIDI sequencer application.
Link: Anthem page
Enigma
An addictive KDE block moving puzzle game.
Miscellaneous C++ libraries
And there's more. Oh yes.
Link: C++ page
Non-downloadable software
My, this section is old. Very old...
RISC OS Anthem sequencer
The original RISC OS version of Anthem (formerly TraxSequencer) was released as a commercial product by rcomp interactive. It met with critical acclaim, and was one of the foremost Acorn/RISC OS sequencers.
View the product page from http://www.rcomp.co.uk/rci/sound/anthem/anthem.htm