Hey firstly LOVE the game. Hugely addictive in a very 'Woah since when has it been 4am' kinda way.
There's been an explosion of sorts of mod interest in this game, and its something that really interests me too. Whilst I know there's been no comment yet as to how the developers feel about modding, I thought I'd get this in for if (when) they come out in favour of it.
The .dat structure being used for files at the moment is all well and good, and people have found a way to modify the contents of these files. However fo ease of use of mods, I think it would be a great idea if the game checked for unpacked files before loading from a .dat file. Any unpacked files the game detects would be loaded instead of looking for the vanilla files in the .dat files. You could even make it possible for modders to create their own .dat files which the game would essentially read like a patch file. This way users can leave their original .dat files completely unchanged (Less risk of a game breaker!) and installing of mods becomes that much easier.