Against 1 e4, there are some interesting gambit ideas in the Scandinavian Defense:
1 e4 d5 2 ed Nf6 3 d4 Bg4 (The Portugese Variation)
1 e4 d5 2 ed Nf6 3 c4 e6 4 de Be6 (The Icelandic Gambit)
Against 1 d4, super-GM Morozovich used to have good results with the Chigorin Defense: 1 d4 d5 2 c4 Nc6. (He doesn't play it anymore, which might indicate that he doesn't trust it against the 2650+ level players he now faces on a regular basis.)
All of the above defenses are recommended and analyzed in "An Opening Repertoire for the Attacking Player (Revised edition)" by Raymond Keene and David Levy.