I'm a big fan of giving gifts that you can enjoy until they're gone. Pie, cake, wine, macarons, flowers, etc. And not just for hostess gifts, but for birthday, Christmas, or just because.
When I stayed with some friends for a weekend, I brought them homemade French macarons and cookies as a gift. Who doesn't love sweets?
Here's a few ideas for hostess gifts.
Macarons: I made some here, and they could be made again to be used as a hostess gift. They were so good though, so you might not want to share.
Homemade Treats: Cookies, pie, you name it. You can bake it, or buy it, though I'd recommend buying it at smaller bakeries, they usually seem better from them.
Wine: This is fairly common, but it is easy to buy a bottle. Some grocery stores have staff that have actually gone to school to lean about wine and those people can be really helpful.
Flowers: Flowers don't seem as common as wine, but they are pretty. Bring a bouquet of flowers to your hostess. I'm sure she'll love them.
What do you think you'd give as a hostess gift?