For leveling:

Shammy 1: Skinning/Herb
Shammy 2: Mining
Shammy 3: Enchanting
Shammy 4: LW
Shammy 5: LW

Mentioned higher in this thread, Herbalism is almost a must have. Even if you don't skill it up. It is a godsend for some collection quests (just remember to loot LAST on your herbalist!) Inside Underbog, it's invaluable for collecting Sanguine Hibiscus.

Collection professions are a mixed blessing while leveling. It really slows things down (I hear the skinning sound in my sleep). But at the same time, I'd hate to go back to low level zones just to skill them up. Furthermore, I'm obsessive. When that yellow dot appears on my minimap, if it's a skill point, I must grab it. In general, I believe having the big three pays off huge in the Outlands instances. So many have ore and herbs. It's easy money with no competetion.

Enchanting is a must have and EASY to skill up if you start when you are a wee toon. All those greens and blues you are never going to use, DE them, and grind out some lowbee enchants. Vendoring blue BOP's and then having to pay for enchanting mats is a lose lose. And you get ALOT of the better enchants from Outland instances.

Eventually, all or most will pick up alchemy as a prof. It's easy to level (I have 3 master xmuters atm), and the low level mats are dirt cheap on my server. Xmuting is great money. It's good to plan for on the way up because you will want to get your sporregar rep while questing in Zangermarsh.

I don't know how feasable it will be to level LW on all of them, of if the BOP gear is worth it. For now, it works on two just to burn thru the main toons skinning mats. With the potential to really grind out alot of badges and gear in heroics, I hesitate to go for professions soley based on the acquisition of craftable BOP gear.

I have two other alts that are JC, so no need for a third and 5 alts that are tailors (3x spellcloth, 1x mooncloth, and 1x shadoweave). Tailoring is good as a money maker (spellcloth is going for upwards of 65g on my server), but serves little utility to shamans. I have one alt that is a BS/Eng. Engineering *could* be fun on the shammies, but I'm not enough of a massochist to level it a second time.