They are safe pretty much forever unless you see mold, etc. They do lose potency as time goes on.

Fresh is always better. Buy the smallest container possible. I don't think they go bad but lose their potency with time. Usually, if they smell strong they're okay.

If Kamut wheat is an indication of expiration date then read on. It was once believed that Kamut was descended from mummified grain found in a tomb near Dashur, Egypt in the 1940s. In 1949, a U.S. airman was given thirty-six kernels of an ancient grain. He mailed the grain to his wheat- farming father in Montana who promptly planted it. Thirty-two of the kernels germinated. The grain was used for cattle feed and was touted as "King Tut's wheat" but was pretty much forgotten. Until 1977. Montana agricultural scientist, Bob Quinn, PhD, saw the grain's potential and embarked on research and propagation. Quinn coined the name "Kamut," which is an Egyptian word for wheat. Mummified Wheat?

You can keep using them, but as they age they loose their pungency.

It will always be safe, problem is the old stuff won't have the effect you're looking for (Spicing it up). Check this yo... http://www.mccormick.com/Spices101/HowOldSpices.aspx

As long as they are dry and kept sealed they are safe to use for many years (15 - 20). Fresh is best for more taste, as they will lose strength over time. +5

Not only do spices loose potency rather rapidly (over a period of months, not years) but they also begin to smell and taste "old" after too long a time in storage. Not a safety issue, but definitely an issue of good culinary taste. BTW, check various brands. The better ones do show either packed-on or best-if-used-by dates. One strategy to ensure freshness is to just buy a full set when you change from standard to daylight time and discard any that remain till that time next year. This message brought to you by the World Council on Herb Production. :)

Whole spices will keep the longest, because they have not been cracked or ground, exposing the volatile compounds which make up their flavor to the air. They can last up to four years in an airtight container in a cool, dry place, and well keep even better in the dark. Extremely strong spices such as whole cloves, cinnamon, and pepper may last even longer. You can tell that whole spices are too old to use when they have lost their aroma. Ground spices have a shorter shelf life, usually between two and three years. They should also be stored in a cool, dry place in airtight containers. To determine whether or not ground spices are still usable, gently shake the container with the cap on. Remove the cap after a moment and smell the container, to see if the rich smell of the spice is still present. If ground spices have declined in quality, you can use more of them in a recipe, with care, or toast them to refresh the flavor. To toast ground spices, use a cast iron skillet or a heavy pot over medium heat, tossing the spices periodically to distribute the heat, and use them immediately. Dried herbs keep for less time, because they are more delicate. Most culinary herbs last between one and three years. Test culinary herbs by crushing them lightly in your hand. If the herbs still smell, they are good, even if the color has changed. If no odor rises after crushing, discard the old herbs. You can prolong the life of your spices by storing and handling them well. Spices do not do well in extreme heat, so do not store them directly above the stove. They also keep poorly in the cold, so freezing them is not advisable. When using spices in cooking, pre-measure them, rather than pouring them over a hot dish. The steam will damage the spices, and if your hand slips, you may ruin the dish. Also always use clean, dry measuring implements when dipping into containers of spices.

Herbs will last almost forever but their taste does not. As they age, You will have to use more of them to achieve the same amount of flavor.

I don't like to keep mine for more than 12 months, they tend to lose some of their flavor and potency after that.