I just read a thread about how to have butterflies fly across screen,(I can't find the thread) but, here is a quick example, which have unlimited possibilties. Its an animated gif over a photo.

http://www.hughmobley.com/Untitled-1.html

Hugh, that thread was in response to a demo posted by one of our users.
In one reply i distinctly remember disucssing Particle Illusion
If you search Particle Illusion in this forum, you'll find the thread in question

it was this thread, about something i had in my demo:

http://dvinfo.net/conf/showthread.php?t=80395&highlight=nice+wedding+effects

for more realism, i would defocus the background while the butterflies are in the foreground, or vice versa. Also, some motion blur on the movement if you can.

And before Peter Jefferson says it, u can use Particle Illusion too and have a butterfly as an emitter :)

HAHAHA, Peter and I were writing our replies at the same time...Peter did beat me into saying it after all... :)

Somehow I just never could make the connection between butterflies and marriage.

yeah funny isn't it, i only did it coz there were butterflies on the wedding invite, and it was specific to that wedding couple...not sure why people are so intrigued by it, but its nice nonetheless.