Found this on a BBQ website
The following woods can be used for smoking:
Acacia - flavor similar to mesquite but not quite as heavy.
Alder - Good with fish, pork, poultry, and light-meat game birds.
Almond - A sweet smoke flavor. Good with all meats.
Apple - Mild. Good with poultry (turns skin dark brown) and pork.
Apricot - Good on white or pink meats, including chicken, turkey, pork and fish. Milder and sweeter than hickory.
Ash - Good with fish and red meats.
Birch - Flavor similar to maple. Good with pork and poultry.
Cherry - Mild and fruity. Good with poultry, pork and beef.
Cottonwood - Subtle flavor. Mix with chunks of other woods (hickory, oak, pecan) for more flavor.
Crabapple - Similar to apple.
Grapefruit - Mild. Good with beef, pork, fish and poultry.
Grapevines - Tart, rich and fruity. Good with poultry, red meats, game and lamb.
Hickory - Commonly used wood for smoking. Sweet to strong, heavy flavor. Good with pork, ham and beef.
Lemon - Mild. Good with beef, pork, fish and poultry.
Lilac - Good with seafood and lamb.
Maple - Good with pork, poultry, cheese, and small game birds.
Mesquite - Strong flavor. Good with beef, fish, chicken, and game.
Mulberry - Like apple.
Nectarine - Good on white or pink meats, including chicken, turkey, pork and fish. Milder and sweeter than hickory.
Oak - Heavy smoke flavor. Good with red meat, pork, fish and game.
Orange - Mild. Good with beef, pork, fish and poultry.
Peach - Good on white or pink meats, including chicken, turkey, pork and fish. Milder and sweeter than hickory.
Pear - Like apple. Excellent with chicken and pork.
Pecan - Similar to hickory. Good with poultry, beef, pork and cheese.
Plum - Good on white or pink meats, including chicken, turkey, pork and fish. Milder and sweeter than hickory.
Walnut - ENGLISH and BLACK - Very heavy smoke flavor can be bitter if used alone. Good with red meats and game.
Other wooods - Bay, Carrotwood, Kiawe, Madrone, Manzanita, Guava, Olive, Ornamental Pear, Ornamental Cherry, Beech, Butternut, Fig, Gum, Chestnut, hackberry, Pimiento, Persimmon, and Willow.
The following woods are not suitable for smoking:
Softwoods or evergreen woods (Pine, Fir, Spruce, Redwood, Cedar, Cypress, etc.), Elm, Eucalyptus, Sassafras, Sycamore, Liquid Amber (Sweetgum), Chokecherry, green Cottonwood.
Other guidelines for smoking woods:
If you have some wood and do not know what it is, do not use it for smoking food.
Never use scraps of treated wood or wood that has had any finish applied. Paints and stains can impart a bitter taste to the meat, give off toxic fumes when burning, and old paint often contains lead.
Never use wood from old pallets. Many pallets are treated with chemicals such as insecticides that can be hazardous to your health and the pallet may have been used to carry chemicals or poison.
Avoid old wood that is covered with mold and fungus that can impart a bad taste to your meat. If you have some good wood that has fungus growth, pre-burn it down to coals before you put it into your smoker.
