The Göring Gambit (1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.c3, or 2.d4 exd4 3.Nf3 Nc6 4.c3 which tends to be my preferred move-order) is looking in quite a healthy state at the moment, in my opinion, as far as sub-master level play is concerned.
At my new chess site, I have published a series of articles covering all important lines of the gambit. I have linked to my articles (which contain an introductory coverage of the key lines and ideas, and then annotated illustrative games).
For those who prefer the style of analysis at my old chess site, where I provided an analysis in PGN format, I have linked to that analysis too.
But for those who just want a summary of the key points, here they are:
A) After 4...Nge7 White can get a small advantage with 5.Bc4 d5 6.exd5 Nxd5 7.0-0.
B) After 4...Nf6 5.e5 Ne4 White gets some advantage in a complicated position. 5...Nd5 is more solid, where in many lines White must settle for a small edge, with pawns on d4 and e5 and some chances of attacking on the kingside.
C) 4...d5 equalises, but White can avoid the irritating Capablanca Variation (5.exd5 Qxd5 6.cxd4 Bg4 7.Be2 Bb4+ 8.Nc3 Bxf3 9.Bxf3 Qc4) by playing 5.Bd3 (which often leads to White playing a gambit anyway), or by playing 7.Nc3, with the idea 7...Bb4 8.Be3 (suggested to me by Mark Nieuweboer). Although the resulting positions are equal, White often scores well in practice.
D) After 4...dxc3 5.Nxc3 Bb4 6.Bc4 d6, 7.Ng5! gives White full compensation for the pawn (instead of the more popular 7.0-0 and 7.Qb3, which probably fall short). Similarly, 6...Bxc3+ 7.bxc3 d6 is met by 8.Ng5!.
E) After 4...dxc3 5.Bc4 cxb2 6.Bxb2 Bb4+ 7.Nc3 Nf6, 8.0-0!? looks promising for White, and White can choose between following up with 9.Nd5, or 9.Qc2 first.
F) After 4...dxc3 5.Bc4 cxb2 6.Bxb2 d6 I think White has some improvements over John Watson's analysis of 7.Nc3, 7.0-0 and 7.Qb3, and all three lines are currently looking playable for White.
So, for those who have been interested in trying out the Göring but have been deterred by certain lines (most likely those stemming from either 4...d5 or 4...dxc3, which are the two theoretically best responses), I think it's well worth giving it a try.