I didn't quite get to my $50 donation goal, but I got more than halfway there, and built an upload form anyway (I'm nice like that). It's pretty basic - very ugly and has a few security flaws (ie: it overwrites an existing file by the same name), only handles .jpgs files, etc, but... it works. It also lets you upload up to five at a time!
If you'd like to troubleshoot it for me before it starts getting serious action, I'd appreciate it: http://hotlink.ellenmilliongraphics.com/sketchfest/sketchfestupload.php
The form will only be active until tomorrow afternoon, to prevent server abuse, but the files will remain up and available for hotlinking after the event. If you are filled with awe and gratitude, you may still donate towards the service:
Join us with prompts once the event gets started! Weeee!