Glow in the dark egg hunt. Could spray paint the eggs with glow in the dark paint instead of using glow sticks. Also, doesn't have to be for Easter. Could be a fun night time scavenger hunt or other fun summer game.
It's been exceptionally nice in Iowa over the last week, so I've been spending lots of time outdoors. If you're enjoying similarly wonderful weather, Dating Divas has a great roundup of outdoor party games you'll want to check out.