What can be nicer than to look for ways to say, thank you, this was great, please have us over again next year? You probably know your hosts (and your budget) well enough to pick the most appropriate gifts. Here are a few options that do not come to mind so easily.
Gift Cards/Coupons: These can be the most flexible and dependable gifts. All we need to do is pick the right one. Maybe something your host will look forward to after all the back-breaking work of hosting you :) A brunch or dinner coupon at her favorite coffee shop or restaurant is an option. Or, a movie (with popcorn) coupon at the closest theater will be a fine way for your host to relax next evening. Sis-in-law suggests a box of candies to go with the gift card. Drop the two into a cute gift bag and you are all set.
Prep bowls ($10 up): They can be simple or fancy, but are always handy to have around the kitchen. Nice way to say you loved what he/she cooked for dinner and would like them to have all the help they need for dinner next year. They are easily available at the big stores and online.
Take a few group pictures with your hosts. When you develop those photos back home, make sure you send a few copies to your host family. With most of us using digital cameras, the easiest (and cheapest) way to share photos is by e-mailing the files. However, mailing prints will probably be more appreciated.
No matter what you do remember to say THANK YOU.