While You’re Away
Hopefully you've thought about this before you even got your pet, but if you haven't, you will eventually have to have a plan for when you go away from home on vacation. Cats are usually fine to leave at home alone for a weekend (leave enough food and water!) but dogs are another story. If you can't take them along, the best solution is to find a trusted friend or neighbor to house-sit or check in on your dog daily, take him outside and make sure he';s fed. If that's not an option, you'll probably have to either hire someone, or board him.
Professional Pet Sitters
Be careful if you decide to use a service like Craigslist! I've actually managed to find several resources for professional pet sitters. It's good to get references, and make sure they have previous experience and/or cartification. Here are a few sites you might want to explore:
National Association of Professional Pet Sitters
Pet Sitters Network
Here is an excellent checklist for finding a pet sitter, from the Humane Society: Choosing a Pet Sitter
Boarding
This is probably the least ideal situation, but it doesn't have to be terrible. More and more pet hotels are popping up that offer excellent care for your pets while you're away. Be sure to really tour the facility, and ask a lot of questions. Make sure that any special needs your pet has will be noted and taken care of. If you happen to meet any customers there, ask them what they think. You can even do a little research online for reviews. There are websites out there that let people comment on businesses. I used Yelp.com to find my eye doctor! If you have a PetSmart in your neighborhood, you may have found one option (see PetsHotel)