I've been rather busy recently, but I've updated the Scotch Gambit coverage (in particular responding to some points from Mark Nieuweboer- there were indeed a couple of GM encounters in the line 4...Nf6 5.e5 d5 line which I had somehow missed first time around).
My next update, which is currently underway, is set to return to the King's Gambit Accepted lines. I have had a good look at the Modern Defence (1.e4 e5 2.f4 exf4 3.Nf3 d5) which, unlike many other ...d5 declining lines in the open gambits, rarely leads to a sterile equality, and both sides retain plenty of scope to play for a win, though in my database White is doing quite well after 4.exd5 Nf6 5.Bc4, as was favoured by Joe Gallagher and Mark Hebden when they frequently used the gambit. Instead the popular 5.Bb5+ variation scores very well for Black. Note that Black can use the move-order 1.e4 e5 2.f4 d5 3.exd5 exf4 here, with the aim of getting into a Modern Defence while denying White the option of 1.e4 e5 2.f4 exf4 3.Bc4 d5 4.Bxd5.
The other important defence is the Cunningham (3...Be7) which can be followed up by a check on h4, or playing to return the pawn and reach equality by playing ...Nf6, encouraging e4-e5, and then ...d6. I have also taken a brief look at 3...Ne7 and 3...h5, the interesting but dubious Wagenbach Defence, which got a lot of coverage in Chess Monthly when Mike Fox was still alive and contributing to "Addicts' Corner".
I am also looking at the King's Bishop Gambit (3.Bc4) and the Mason Gambit (3.Nc3), which includes a look at the related Steinitz Gambit which arises after 3.Nc3 Nc6 4.d4, again encouraging Black to check on h4 and bring the white king out to e2. After 3.Bc4, 3...Qh4+ is still playable but not as strong, as the white king is relatively safe on f1, so Black often opts for a different approach. I don't intend to examine other white third moves as I don't think they are particularly promising for White or difficult for Black to handle.