Probrably easy to implement?
I really really want Boarderless Fullscreen to be added to NS2. For those unaware, this feature allows you to run the game in a window without a boarder at full resolution (or any other if you want). Basically, its like running the game in fullscreen, but gives you all the advantages of running in a window like fast alt-tabbing and allowing other windows on top of the screen. My hope is that the appropriate options are added to the options screen eventually (sooner rather than later).
Games that have it are basically all valve and blizzard games. I'm guessing there is probably a way to implement this already without the devs having to do anything, but I am so far out of the loop when it comes to modding, I'm not one to figure it out myself.