Sega is bringing some classic arcade and console fighters over to PlayStation Network and Xbox LIVE Arcade shortly. Specifically, you can pick up Virtua Fighter 2, Sonic the Fighters, and Fighting Vipers.
Each runs five bucks, and will hit PSN in North America next Tuesday, November 27, and Europe December 5; the XBLA release is set for November 28 (worldwide). I've heard nothing about PC versions, except to say Virtua Fighter 2 has been available via Steam for two years now, and for three bucks instead of five (although it doesn't include achievements or online play, as far as I can tell).
The games will include online play, achievements, and trophies, and serve as "complete versions" of the arcade originals.