a.s.a.p. = as soon as possible
t.b.a = to be announce (at a later time)
c/o = care of (additional information in an mailing address)
cc = carbon copy (an old reference to when carbon paper was used in a typewriter to make a copy)
enc = enclosure (denoting a document has been added to a letter, snail-mail and e-mail)
i.e. and e.g. = latin terms meaning, "for example". I don't know the difference between the two.