It seems as though White can easily dominate the tempo in a blitz game through a strong, aggressive opening. Is this the case? What openings are strong for White when there is a short time limit (e.g., in blitz)?
I think this depends very much on how strong you are.
That said, I had some success with the Ponziani. It is not the "best" opening, but solid, and many players don't know it and lose some time thinking about the next moves. The theory is easy, and there are several traps black can fall into (my favorite is when black takes the "unprotected" e4 pawn with the knight and you can fork it with
Generally it might be a good idea to play aggressive (e.g. Steinitz'
Qh4 in the Scotch game) and to try to throw the opponent out of the book as soon as possible. Of course the opening must be still playable, and you need to know some theory.
There are plenty openings you could use in blitz, but, i think the slow solid and positional openings need more thinking, thus you could lose. I would suggest playing like Mikhail Tal, make sacrifices without calculating the move too much, and try to complicate the position for your opponent. I have used this in many of my games,i complicate the position, Make a complex but possibly unsound sacrifice which confuses the opponent and the opponent might choose the wrong variation and lose trying to play fast, or, might think long, get the perfect move but finally lose on time. so the clock is also a thing you will need to think about in blitz.If you want me to suggest openings, then From white the kingspawn,Maybe kings gambit, the open sicilian which is my favorite,scandinavian and such.French is a solid opening from black and either play advance and lose time for your opponent or play the exchange variation. With the black pieces, against 1.c4 Nf6 i think is the best way to respond and after that try to enter the indian system, Nimzo or kings indian. For d4 i would say Nf6 isnt bad but it involves more thinking,so i like to play the dutch defence, leningrad variation which is not very popular a chess opening.iwold definately suggest sicilian defence Najdorf variation in blitz, though it seems very impractial because ofthe sharp lines and tactical,calculative pplay, as mentioned before you can confuse your opponent into time pressure, and of course though i recomend to do unsound sacrifices maybe, but this should be used very rarely and in very important positions. Remember, even if your playing online you are psychologically twisting your opponent into a very uneasy place.