Which Items Make the Best Giveaways?

We are going to start going to career fairs and trade shows, and we need to get some promotional items made to use for giveaways. Can anyone tell me what people like to receive the most? We were thinking that at least for the trade shows we might want to have promotional mugs. The career fairs we might have something a bit less expensive, but we’ll have to see what the costs are and what items are available. Can anyone recommend a good company that makes this sort of item so we can get an idea of what things we can have made and how much they cost?