I was reAding through Life Hacks (some great tips), and the question was asked about carrying condoms. There were a few practical tips but no one mentioned Trojan 2 Go condoms. The package is specially designed to carry the condom in your wallet with out compromising the effectiveness of the latex. The packaging is hard and a little larger than a regular condom wrapper, so it may be to big for some wallet's (yes, pun intended).

http://www.amazon.com/Trojan-2-Go-Ultra-Thin/dp/B001XVU1PO

Edit: They are found at the register in most pharmacies instead of the condom section.