i use too in the past, havent in a few months ... i've also uploaded high res images to servers to give away for free ... now, just cause someone downloads your photo, doesnt mean they have copyright
if someone "steals" my photo, actually .. i would be quite flattered that they would go through the trouble

... however, i "give" quite a few of my photos away (allow many to use them for their website, publish, etc) ... but i have never transferred the copyright to anyone.
the way i see it, its like spreading a seed .. if your photos are out there all over the world enough, someone is gonna start asking questions .. "who took that photograph?" .... i wanna spread my joy
now if someone uses my photo and claim it to be their own (they claim to have taken the photograph) ... that would drive me mad and if i find out, i would take them to court over the principle :x