The most common symptoms of gluten sensitivity infolve the gastro-intestinal track and include bloating, abdominal pain, diarrhea and/or constipation.

Other common symptoms include a lack of energy, fatigue or a feeling of "mental fog"

Many people with gluten sensitivity develop rashes.   The most common rash associated with celiac disease is called Dermatitis herpetiformis, but many other types of rashes can develop as well.

Individuals with Celiac can also develop vitamin deficiencies because nutrients in the small intestine are not absorbed properly due to the inflammation.

Grains which contain gluten and that should be avoided are barley, rye, and wheat.

Foods that contain barley may include: pastries, pie crust, pizza dough, pumpernickel bread.

Foods that contain rye may include: breakfast cereal, rye bread

Foods that contain wheat may include: bagels, bread, cookies, couscous, muffins

Some not so obvious foods that may contain gluten include potato chips, salad dressing, sauces, sausages,
soups.

These foods do not contain gluten:

Beans (but be careful of what's added in baked beans)
Buckwheat
Corn
Egg
Flax
Fruits (fresh)
Cow milk
Nuts
Potato
Rice
Soybean
Tapioca
Vegetables (fresh)

Foods that contain barley may include: pastries,

The Celiac foundation is a good place to start.

Celiac.com has a lot useful information on Celiac disease and how to go about a gluten free diet.  Just watch out for all the ads everywhere!