MIDI for Musicians by Craig Anderton is a classic that's as relevant today as it was when it was written since the MIDI spec has changed scarcely at all over the years. If you compose using MIDI (and I just happen to know that you do), you should have it on your shelf. $13.
"The Samplist" looks interesting. I read it's about a failing music student . . . if I ever take I music class, that'll be me! I'll be able to relate to it . . . maybe . . . I don't know much else about it . . .
Thanks for all the suggestions, now I really have no idea what to get . . .