Don't let the dark scare you: This 5/10K race will be illuminated by its runners, wearing glow-in-the-dark bracelets. The second annual Firefly Run Chicago kicks off in Grant Park at 7:30 p.m. Sept. 7, and proceeds will benefit the American Red Cross of Greater Chicago. Registration costs between $35 and $50. Sign up online at the Firefly Run's website.