Hmm, let's see if I remember Hebrew class.
Blood = Hapi, Nile God
Frogs = god of childbirth (had something to do with frogs, dont remember)
gnats = ?
flies = Kheper, god of flies
cattle = Apis, god of the bull
boils = Imhotep (healing)
hail = duh, sky god - Nut
locust = god of farming, agriculture (set? seth? something like that)
darkness = you got it, Ra
first-born death = As I recall this was more directed at Pharoh who, at the time, was viewed as the link between god and man.