I've lost a few myself. Once that little guy is gone, you've rendered your tripod quick release plate pretty much useless. You can order these replacement screws through some of the big retailers for over $10 dollars, or you can check out eBay for some cheaper prices. Problem is you've got to wait weeks for that over seas shipping, so might be something small to keep handy. Call it Preventative Maintenance..

1/4 x 20 Replacement Screw for Quick Release Plates
[Update] This one would work out as well, but doesn't look like the standard 'slotted' screw head, where a quarter comes in handy. https://www.bhphotovideo.com/c/product/302185-REG/Wimberley_SW_100_Extra_Screw_1_4_20.html

Ignacio
Be careful with adapters. This is a Manfrotto one:
https://img855.imageshack.us/img855/2286/img1282peqmas.jpg
Emm
Post author@Chris Winter - You can just grab any simple 1/4 x 20 bolt from the hardware store. These have a special cut out towards the head to fit into slotted tripod plates.
Chris Winter
Hey Emm,
Is this the same that came with the Flycam Nano? I lost the little bugger!
Paul
https://www.bhphotovideo.com/c/product/302185-REG/Wimberley_SW_100_Extra_Screw_1_4_20.html
Here's a $1.95 version and three favorable reviews over at B&H. Note that you will need a hex screw driver on these. Don't have personable experience with this one but the price is right. Will pick up a couple of 'em next time I order from good 'ol B&H.
Emm
Post author@JayK - Sorry, I think it's working now.
JayK
sorry, link doesn't work here. What do i have to search for?
Rod Parmenter
Thanks- This is very helpful!