My compositions are polished over weeks to months. I notate each by hand and either synthesize the results (particularly if the piece is orchestral) or play them very carefully. However, the majority of the effort is not in thinking up the music, but communicating it. I also improvise pieces on the piano in realtime, a select few of which later become full compositions after receiving much attention. A composition that takes half a year to write may get its start from a theme that took two minutes to play.
There's a reason for the cleaning, however. When writing things up on the spot, I try playing new chords, going in new directions, and just generally trying to get the music down. I'm not concerned with the accuracy of the performance; in many cases it's abysmal. I frequently decide I didn't like a chord, so I just go back and play a different one. Sometimes it takes 3 or 4 tries to find the right one. I just want a record so I can come back to the theme later.
In other words, these pieces sometimes encapsulate good musical ideas but are usually performed poorly!
I am now sharing these records, poor performances and all, with you. Listener beware: this is an uncut view into how I create some of my pieces. It is very much alpha-stage work.
The 
icon denotes a piece I happen to particularly like. That doesn't necessarily mean the quality is higher.
Still want to go ahead? Clicking the 
icon will download a MIDI of the piece (really small, but the sound quality won't be great unless your sound card is), while clicking the 
icon will automatically synthesize and stream an MP3 from the performance on the spot and 
will download the synthesized MP3. Audio synthesis may take up to one minute before the file is ready, and you'll be downloading a MB-scale audio file rather than a KB-scale MIDI, but the sound quality will be better. All of my mistakes... in crystal clear sound!