Hope this is the right place for this. Going to plug my company lightleaks.me - we create light leaks and transitions for editors/filmmakers.
Currently, we're giving away some free light leaks to anyone who signs up to the mailing list - we do promos and giveaways every now and again too.
Our light leaks work with all major editing programs. It's pretty easy actually. Drag you favourite effect onto the timeline, directly above your footage. Set the blending mode/composite mode to "screen" and play it back. You can customize the effects any way you like. Try changing the speed, color and opacity. Here's a how-to video
Enjoy and let me know what you think :)