I'd like to see some more variety of grenades. Drawing on the real world for inspiration:

A delayed timer variant that doesn't begin counting down the fuse until you throw. (This is how real grenades work. No one wants to pull the pin and then be carrying a ticking bomb...) For extra usability, some way to put them away if you decide not to throw them would be great, but just being able to run around with a grenade in your hand ready to be thrown could add plenty of emergent tactics we don't have now.

A defensive grenade variant. Defensive grenades are grenades that have a blast radius larger than they can reasonably be thrown. They're usually packed with more explosives making them heavier (so they have both a bigger blast radius and can't be thrown as far.) and are designed to be used when you have cover to throw them from behind. They're the kind of grenade you would toss through a doorway before stepping back, or throw over a low wall where you'll be shielded from the blast. In DUST, I was thinking something along the lines of the shorter throwing distance of the Packed AV grenade variant, with roughly the same damage that AV grenades currently do to infantry without their soon to be implemented vehicle only usage.

A few other grenade ideas gathered from the IRC channel...

Flashbang variants. Large explosion radius, little to no damage (just enough to give everyone hit markers and cause a bit of confusion), just a very loud noise, bright flash, and some smoke left dangling in the air. On the plus side, great to use in game modes where friendly fire is on and you don't want to have to explain why you threw a Frag into the middle of a gunfight.

EMP Variants. I'm not sure how possible it would be with the damage types in DUST, but a grenade that did massive shield damage and ONLY massive shield damage. Basically you would never be able to get a kill with these grenades, but you could instantly drain an enemy's shields and then finish them off with gunfire. An AV variant of the same would also be nice, something to take the (obviously superior) shield tanking vehicles down a peg or two.

I'm guessing someone who's been deployed can vouch that they still do this.

do they still make you do that wonky "shot put" style throw for grenades?

As someone who's been deployed, I can vouch we'd never do this. Fuses in the real world have too much room for error, leaving the timer between 3 and 5.5 seconds. So if you pulled a grenade pin and counted to 2 before throwing, you'd have a grenade with between 1 and 3.5 seconds left before exploding, which is too large of a window to try some of the airbursting tactics you see in video games and movies.

How about a floating cross hair on the ground that shows the point of impact for mass drivers? Even moderate distance firing takes ranging your shots and with moving targets like a tank that just flew by, hitting them is almost impossible.

LASERS