I just made a batch of kimchi this weekend, had a taste last night and it's too salty! What can I do with it?

Unfortunately, rinsing kimchi also rinsed the chili peppers off, so it would be quite bland. It sounds like it needs more fermentation. I wonder if you could mash more cabbage into it?

I'd give it time for sure--I usually wait at least a week, but how do you like to use your kimchi usually? If you will be using it in cooking, then you can generally make it work. Aside from rice and soup, I put it in grilled cheese too (I was suspicious, but this is the bomb).
If you like it as a side dish, then you could make a second batch with less salt and mix them.

If this is an instant kimchi recipe (ready approx one day after mixing) and/or you want to use it in the next day or two, rinse as suggested or mix with other (non-salted) foods to dilute and eat.
If not urgent to use, let it ferment a few weeks in the fridge and taste again.
Last, I looked at a few kimchi recipes I use and noticed an approx ratio of 1/2 cup salt to about 6 or 8 cups shredded raw cabbage. If your recipe is in that range, not to worry and wait for kimchi heaven.

You could definitely do fried rice as Antonia suggested. That is a common way to eat it. You can also put it in soups as the liquid will dilute it just go easy on soy sauce and fish sauce. The kimchi will be your salting agent. I would recommend when making the fried rice or soup add maybe 1/2 to 1 tsp of sugar or honey not to make it sweet but to round out the salt. That is a common technique in Thai food as well.

Perhaps rinse it? That's what one does with sauerkraut (kimchi's first cousin). I've never made kimchi, however, so I don't know for sure. ;o) P.S. Fried rice sounds great. Or into stir fried noodles! Or in roti wraps or tacos, making sure the other ingredients are not salted at all, or much.