I would like to say that when talking to this with my friend he ask me, hey could we play warhammer 40k with that?
I started thinking about this and realized that Roll20 could easily be used for mini wargames in addition to pen and paper games. However in order to do this several systems need to be added (many of which have been suggested before). This could expand the customer base of people who use this application
1) Abilitiy for players to control their own tokens (so you can make your own moves)
2) Ability for players to use a measure tool (same as above) and adjust that tool as needed. For example be able to change how the tools measure so that 1 hex=1 inch..etc
2) Ability to be able to place tokens off a hex to allow more freeform placement of tokens, that way you still have the grid to be able to measure distance
3) Ability to upload PDFs by player and GMs (so each player can see exactly whats on the others army list).
4) Ability for player to upload their own images (either requires GM approval or is a settings that can be turned on/off) so they can use their own tokens for their army (like say pictures of thier real army).
5) Ability to turn tokens in more specific intervals (for example you can pick to turn a token 90, 45, 10, 5 degree increments) for those games where facing is important.
This could also be solved by allowing more than one GM in a game.
By doing this you can add another category of games without adding a bunch of system specific options. All the above could also be used by the pen and paper side.