Wooooooowww! They look great! I think they are a kind of oil/blister beetle (related to the ones they get "Spanish Fly" from). The family is Meloidae and from a quick scan around the web, I reckon they are berberomeloe majalis. I wouldn't touch them though, as such beetles are highly likely to exude a chemical called Cantharidin which will burn your skin...... very badly!
Trev