Recently, I came into the possession of two cases of pure mango juice - 12 tetra packs of one liter in each case, 24 liters of mango juice in total. That's a lot of mango juice.
In addition to drinking it, I decided to try using it in sauces, via the reduction method. In case you don't know, that's pretty much exactly what it sounds like - you reduce the liquid by simmering, which drives off the water and concentrates the flavours (and the sugars). When you've reduced it by 3/4 or so, and you cool it, you're left with a thick, concentrated juice (think concentrated orange juice in the freezer at the grocery store - same idea).
On its own, this makes a great glaze for chicken or fish.
Something else you can do with it is add some hot sauce just before you're done reducing it (I added two or three dashes each of a habanero-based sauce and some Louisiana-style cayenne-based sauce). It ends up being a great sauce for stir-fry; it starts out sweet and ends with just a bit of a burn.
Again - this concentrates the sugars in the juice, so if you're concentrating on the low-carb aspect of paleo, this isn't the best idea. However, it won't give you any more sugar than was already present in the juice, so as an occasional treat (and to help convince your friends who aren't sure about this whole "caveman diet" thing), it's not bad at all..