A continuation of a program I wrote a few years back, this little app lets you use your computer keyboard as a piano keyboard:
It can be useful for recording fragments of melodies or songs. The results are saved as a standard .mid file. Also, because it supports easy multi-tracking, it can be fun to make a little song by combining a bass part, harmony, and melody with different instruments for each voice.
(Midisketch sends out real time midi events. So, if a midi loopback driver like Maple or LoopBe1 is used, it can act like a midi input device as well. In fact, it might be interesting to have Midisketch install keyboard hooks like Ctrl-alt-a, Ctrl-alt-b, and so on, that would play the corresponding notes even when the program is minimized. Then it could be used just like a midi keyboard, and recognized as such by other software).
Anyways, here is a short video showing the keyboard: