Sorbet? e.g., pierno's blood orange http://www.food52.com/recipes/9579_ruby_heartstealer_valentine_sorbet

I'd definitely think sweet (dessert) with Moscato. You can use it in a zabaglione, instead of Marsala, or poach or roast fruit with it. Maybe even use it in a trifle, with lots of berries, etc. (Btw, I've also never seen wine in a pasta al'arrabiata...now, a glass - or three - to drink with it is another story ;)

To be honest I've never seen a recipe for anything al'arribiata that actually called for wine. Vodka would be interesting as most of it will burn off. But I wouldn't carry it further than that. Key components are tomato, garlic and a generous amount of hot pepper flake. Chopped parsley is good.

Put some fruits to soak in the moscato, and either eat them as a fruit salad or serve it over pound cake, or even ice cream.

I figured. But I can't drink it! Any suggestions for what else I might do with a half-bottle of syrupy sweet moscato?

It would be awful! Arrabiata is a spicy, garlicky, tomato-y sauce, an angry sauce, in the best sense. Moscato is slow and lugubruious, honeyish and reminiscent of dried fruit. A total clash. You can replace the dry white wine with vodka, sherry, a prickly red like a young sirah or just skip the wine altogether and add a bit more olive oil. Enjoy!

Moscato isn't dry at all - I think its sweet flavor would totally change your sauce. I would go for a red over that, if you had it. Something else for acid - a touch of white wine vinegar or lemon juice instead might work.