What are some things you have done to boost morale in your section/PLT?

As SL on JI, I would randomly conduct in-ranks inspection, then release the sharpest Soldier for the day. I also released Soldiers who wanted to get boat licenses (JI is ~800 miles S of Hawaii) during the duty day, then scheduled a squad (17 Soldiers) cookout and boating day.
As PSG, I dispatched a 2 1/2 ton and took the entire platoon to the education center for a briefing I had coordinated solely for them. After the briefing, I informed the Soldiers that anyone who signed up would be permitted to return from upcoming platoon level FTX for evening classes (straight to class, straight back).
I assigned a list of tasks when I first took over as PSG, which included moving items stored in vehicles and trailers, that should have been stored in connexes. At the end of the duty day formation (PLT level), I asked the SL if everything had been completed (I knew it hadn't). I released the Soldiers, and had the SLs complete the tasks. (Soldiers don't mind working, but they do mind sitting around in the motor pool wasting time. They especially dislike having to work late, or to redo a task because they weren't properly supervised. Improved morale knowing everyone, including NCOs, would be held accountable.) I released the PLT when all training and tasks had been completed for the day, rather than wait until the end of the duty day. Fought to get on post schools and a couple of slots for jumps for foreign wings, which went to most deserving Soldier-not the PL, PSG, or SLs.

I have found that a lack of morale usually come from either being TOO challenged, or not challenged enough. Figure out which and flip the script. If the j-o-b is overly stressful, set up a series of informal gatherings where Joe can de-stress, like BBQ or bowling or (no, I'm not kidding) a class at the MWR arts and crafts center on the weekend. If they are under stressed (usually a result of being disregarded / underestimated by higher), then challenge them. Rigorous PT that incorporates Soldier skills (like land nav or buddy carries), quiz them throughout the day about their job, randomly show up at the barracks with a white glove. Make sure they know that you expect them to be THE BEST and you will do everything you can to ensure they don't slack off.

Either way, I recommend you find a balance between the two after a couple of months. Keeping Joe motivated is a fine art, and requires a good balance of challenges and "lay-ups" but if you challenge them enough, what used to be tough with soon become a lay-up.

When all else fails be the meanest (tough, but fair) SOB around and give them something they can come together on - hating you. I call this the Gunny Highway method. Exacting standards, with no excuses, and no room for argument. Your way or the highway, and at a double time, either way. It sucks, but sometimes that is the route needed to bring a PLT together. If you have to take that route, make sure there is a peer or subordinate NCO who they can turn to to vent and express their frustration with that rotten heartless SOB who is their section leader. (I am not saying to abuse them, just to ride them HARD.). This route takes time. Morale will improve VERY slowly, but cohesion will come along fairly quickly. Once they mesh, they will start slowly meeting your "too-high" standards. And they will slowly realize that they are meeting the standards, and then look around at the other sections who are not. And esprit will follow.

I added a reward based system. If you overachieve for the week out of everyone you get a half day pass to be used whenever. Also hikes as a section once a month. Barbecues for lunch every two weeks. Best way to reward a soldier is with time and money.