Druid’s can benefit from most of the professions available in the game. Blacksmithing and tailoring are typically not good crafting choices, as there are very few items that they can make that are useful to a druid.

Gathering Professions

Herbalism
A great choice for druids, as they can harvest herbs without leaving travel form, cutting out a lot of the down time other classes experience when harvesting herbs. If you are not interested in making your own potions, many herbs sell for a great deal on the auction house.

Mining
Still relatively easy for a druid to use, although unlike with herbalism you do have to shift out of a form to mine a vein. Druids will typically pick up mining in combination with engineering, or just as source of money by selling the metal and gems they find on the auction house.

Skinning
The obvious choice if you plan to be a leatherworker so you can provide your own leather for crafting. You can skin things in forms, and higher level leather is sellable on the auction house for a decent amount. Combine skinning with either herbalism or mining if all you care about is making money.

Crafting Professions

Leatherworking
Allows you to make your own armor, although in general, with a few exceptions, you’ll find armor that drops off monsters is superior to crafted gear. Choose leatherworking if you like the idea of crafting, and for the few high end recipes that are very worthwhile, but don’t expect to make every piece of armor you’ll ever need.

Alchemy
Allows you to make a wide variety of potions, some of which are very useful. Since you can harvest herbs more easily than most classes by picking them in travel form, this is a good choice for any druid.

Enchanting
Enchanting is as valuable to a druid as to any other class. There are wide variety of enchants that any type of druid will find valuable. While it can be tough to make money selling enchants, it is possible to make a good amount by simply selling the enchanting materials you’ll get from disenchanting weapons. Like Alchemy, enchanting is a fine choice for any druid interested in crafting.

Engineering
If you are interested in PvP primarily, engineering is a great choice, as it provides a number of handy items and tricks that can turn the tide of a PvP battle. It is less useful in most PvE situations (especially in the end game), so if you only plan to engage in PvE content, its probably not the best choice.