Resources for music composition?

I'm curious if anyone has any good resources for learning music composition. My situation is that I've studied music for years, including being a music student for my first 2 years of college. I got out of music for a while, and am getting back into it now. I'm interested in learning more about music composition, but have been unable to come up with good resources on the internet. I know a lot of music theory (though have probably forgotten a lot, too), and have done some basic counterpoint exercises in the past. I can string together some nice chord progressions, and sometimes even a decent melody, but developing a musical idea into a full-blown song or other piece of music is more difficult for me lately. So I'm looking for something along those lines.

If it makes any difference, I tend to like instrumental music with American pop sensibilities. I play piano, cello, and tenor ukulele.

If this would be better under the "music" group, feel free to move it there. I was unsure as the music group seems to be oriented towards listening rather than creating.