This was kind of inspired by fencepost's Matrix tute (which I haven't actually done yet...I just got to thinking, how could you do a matrix effect with only Gimp filters?).
Anyway, this uses Courier 10 Pitch Bold typeface (came with my Xubuntu distro), in a .gih format (like the pencil sketch or sparkly brushes, it changes as you brush). If you set fade out, it gets kinda interesting
http://www.deviantart.com/deviation/52663898/Actual brush size is small, only 18 W x 23 H.
Edit: I experimented and made a quickie "matrix" image using the brush.