D&D: Is gridless combat possible?
D&D's tactical movement rules generally assume you're using a squared grid that everyone can consult to remind them of their postion. Since online play has no grid without special software, I'm looking to work out a system of handling tactical combat without any grid. Feel free here to make suggestions.

Problems
Since there's no grid to act as an authority on who stands where, it's easy for desynch to occur between players' ideas of the battle position. It's similar to the problem of blindfold chess, where players each try to hold the entire game in their head. (I imagine that real war has always been plagued with a similar issue.)

Players might simply trust the DM to hold the canonical position in his head to settle disagreement, but the DM is still not infallible. Further, the more complex the combat, the greater the risk of "desynch". Thus, for anything but small combats, any system must be much simpler than the traditional strict grid.

Combat Area
An idea I've borrowed from a fellow DM is separating each combat into two zones - simply, you're either inside the Combat Area, where the fighting takes place, or you're not. Anyone can attack anyone else within this area. A move action allows you to enter the Combat Area or withdraw.

Combat under this system is a lot more chaotic and perhaps realistic. You take attacks from nearby opponents you didn't realise were adjacent to you. However, it raises issues - can you fire from out of the brawl into it? If so, can opponents break off to give chase and enter combat to create multiple Combat Areas? If not, can a wizard use spells without firing into melee? How are flanking, area effects and cover handled?