I got this jazz app on my smart phone, ireal pro. First, I didn't know what it could do, so I didn't use it much. Then I realized you could go to a forum and download countless songs: the app will play the chord changes in the tempo and key you designate, so I downloaded the 1300 jazz standards. You know, Body and Soul and All the Things You Are and the other 1,298 songs everyone should know. I was happy.
So today between classes I look at it and see a little "+ "button. I push it and it invites you to put in your own chord changes. It gives you a template for a AABA song, so I push that, and enter the changes for the first song I ever wrote. Compared to a music notation software program, this was the easiest thing I've ever done, and it took me only 15 minutes to enter the chords. You can name the song, designate the key signature, the tempo, style, and save, and edit it more if you don't do it right. You can make your song into a Bossa nova or anything else.
It gets better: the app will actually play you back your own song with drums, piano, and bass. Needless to say, a generic arrangement, but it works for me. Now I can play the song for other people (the chord changes at least) or put the phone on a blue-tooth speaker and improvise to it singing or playing piano in any tempo or key I want.
I am pretty much in heaven.