J. Martin Plumley's Introductory Coptic Grammar
I must admit that I have not used this introductory grammar much myself, preferring the Lambdin introduction. But Lambdin is not that easy to get hold of and it is a little expensive, so this service over at Metalogos is a superb one, all the more so in the light of April DeConick's recent call for compulsory Coptic for all:
No one who studies early Christianity should be allowed to graduate with a Ph.D. without having learned Coptic. There are too many early Christian documents in Coptic for it to be considered just an "additional" language any more.Update (Wednesday, 7.49): Judy Redman has comments, with links, in a post on Update on Plumley’s Coptic Grammar and other Coptic resources.