As pointed out in other threads, BF is lacking in the area of modern military accessories. I have some ideas to help fix that:
1. Boonie hats, something that I've searched tirelessly for on multiple custom part sites but have come up empty handed. Some people say that the Johnny Thunder style bush hats work, but it would be nice to have a more authentic military look.
2. Shemaghs, again, some would say that neckerchiefs are fine for use as a shemagh, but the tactical scarf is an important piece of military equipment, especially in desert operations. It would be cool to have some for your minifig troops. They'd also work for Indiana Jones and Prince of Persia minifigs.
There are several other things that could also be included for use in modern military setups.