ok, let me share mine.. :)
for my relationship with my 2nd ex, which lasted 3yrs+, broke up cos we didn't believe in long distance relationships...

on her birthday, after a romantic dinner, i brought her to "small genting" in cheras...

I've bought a large balloon and filled it up with helium and put a small lightbulb powered by a button cell (as light as possible)and tied a ring at the knot of the balloon using a "quick release knot"

i asked her to close her eyes, and i went to get the balloon from the boot of my car, asked her to give me her palm facing upwards and i slipped a plastic ring tied to the ballon to her middle finger... (the real ring can't be seen cos the balloon was quite big...

then i asked her to open her eyes, while i hold the balloon, she was surprised to see a balloon... so i told her to write her birthday wish on the balloon with a marker while i am not looking, (i was still holding to the knot of the balloon), then after she was done, i told her to tell me to release the balloon to the sky, and her wish would come thru...

she didn't know there was a string attached...
and so she told me to let go..
she was surprised how come there was a plastic ring thingy on her finger...
after i let go, the string was about 2 metres long, at the end string, which released the "quick release" knot, the real ring fell into her palm...
she was so happy, she used my shoulder to wipe her tears of joy...
after that, I asked to cut the string so that the balloon will fly off with her wish...
she pulled down the balloon, cut the string, we watched it flew off, then she tied the string to my wrist and said, "Now my heart is tied to you, do you have any regrets?"

I just smiled and put the ring into her middle finger...
too bad she had to fly off to australia...
and she just got married in Singapore.. :)