The following grains and starches contain gluten:

barley
bulgur
couscous
farina
graham flour
kamut matzo
rye
semolina
spelt
triticale
wheat
wheat germ

The following foods often contain gluten:

beer
breaded foods
canned baked beans
cereals
cold cuts
commercial bullion and broths
commercially prepared chocolate milk
egg substitute
energy bars
flavored coffees and teas blue cheeses
French fries (often dusted with flour before freezing)
fried vegetables/tempura
fruit fillings and puddings
gravy
hot dogs
ice cream
imitation crab meat, bacon, etc
instant hot drinks
ketchup
malt vinegar
malt/malt flavoring
marinades
mayonnaise
meatballs, meatloaf communion wafers
non-dairy creamer
oat bran (unless certified GF)
oats (unless certified GF)
processed cheese (e.g., Velveeta)
roasted nuts
root beer
salad dressings
sausage
seitan
soups
soy sauce and teriyaki sauces
syrups
tabbouleh
trail mix
veggie burgers
vodka
wine coolers

The following are miscellaneous sources of gluten:

cosmetics
lipsticks
lip balm
medications
non self-adhesive stamps and envelopes
Play-Doh
shampoos
vitamins and supplements (always check labels)

The following ingredients are often code for gluten:

avena sativa cyclodextrin
brown rice syrup
caramel color (frequently made from barley)
dextrin
fermented grain extract
hordeum distichon
hordeum vulgare
hydrolysate
hydrolyzed malt extract
hydrolyzed soy protein
hydrolyzed vegetable protein
maltodextrin
modified food starch
natural flavoring
phytosphingosine extract
samino peptide complex
secale cereale
tocopherol/vitamin e
triticum aestivum
triticum vulgare
yeast extract