Are there gift certificates for air travel or hotels?

My parents keep bugging me about putting together a Christmas list but most of my needs are traveling expenses. It's obviously too much to ask for a $1500 trip to San Francisco for Christmas but are there any types of gifts certificates or what-nots that my parents could purchase that could reduce my traveling expenses?

YES!
Most Chains such as Marriott, Holiday Inn, and Hilton have websites where you can sign up for frequent stay programs that earn you points towards free future hotel stays.
Some wealthy neighborhood supermarkets have racks of gift cards you can purchase at checkout which include hotel gift cards, Disneyland tickets, gift cards to chain restaurants, and the like.
You can sign up with mypoints.com to earn points towards travel gift certificates on your own throughout the year, so you don't have to beg your parents for travel money next time around.

There are
giftcertificates.com has a whole travel section. You get the cert. from this website then you can pick between everything from Carnival cruises to Southwest airlines. They have travelocity hotels and Marriott hotels. Worth checking out.

Also Southwest has gift certificates in our local grocery store.