What alternative forms of punishment have you used to discipline your soldiers without ending their careers?

When the screw up was failing to pay attention to detail, one time I stabbed the wall with a ball point pen a whole bunch of times, then had him count it out...and then verify twice. But I found that creativity is key to my method, as it lets them know I am consistently taking individual circumstance and traits into my decisions. Doesn't work for all, but did for me.
When failing to follow AFI or other reg, I often chose to have them write essays with summation, cross reference, impact on mission and personnel, and a personalized motive to support said reg. 5 spellcheck fails, and you do it over - attention to detail.

had a PVT cut the grass with his fingernail clipper for extra duty for a few weeks and no article was needed

I used a very simple decision process... was there malice intent involved? So, if a sailor screwed up but it was because they didn't know better, forgot, or were rushed because we as a command couldn't plan, then I brought them in for a little informal counseling. As a Chief Engineer, I had a lot of jobs that always needed doing that I could have them do. I eventually pushed this kind of stuff down to the DIVO's and Chiefs after they understood what my boundaries were.

If malice was involved, then they went straight to the formal disciplinary system. We always took into account the sailor's entire career before punishment. I never felt that a sailors career should be screwed up by one single mistake (most of them anyway, some were automatic Captain's Mast).

This only worked because I kept my upper chain of command informed, and they had similar ideas. I also kept my Chiefs in the loop and got their input.

I also believed, that if a sailor screwed up badly, and went to Captain's Mast, that after punishment was served, then they had a fresh slate. I never carried a "grudge" so to speak. If they served their time then let's get back to work. I found that sailors were a lot less likely to get in trouble if they knew you were fair, tough but fair.