I've come across a few, promoting both couples but are sharing the links of the two best sites, IMO.
If you wish to search on your own further, then they can via the several links posted onto each website, though, I'm sure most of you guys know that to begin with.
This site is mostly Ed/Winry art along with general FMA art.
http://2.pro.tok2.com/~brave81/main.html
This is mostly Roy/Hawkeye art.
http://fumiatsu.hp.infoseek.co.jp/top.html
I'd like to thank