Free Program with Piano Roll

[BeniRose]

Hey guys, I just showed my friend how he can control his Juno D with a computer using the piano roll in Logic via a MIDI interface (I just used the one out on the back of my m-audio radium). He was pretty impressed, but he was wondering if there were any free programs that he can do piano roll work in? I know Audacity can pretty much do everything on the audio end these days, but I didn't think it had any sort of MIDI controls.

Is there a good open source or free program that's basically just a midi editor that works mostly with piano roll and piano roll patterns or regions? Something like a dumbed down FL Studio would be cool.