I love crafting. Every game I play, I strive to make most of my own equipment. I Wow, this led to me playing multiple alts because no one crafting profession gives you everything you need, and they all require on the other crafting to some degree for raw materials.
This is not me trying to write a guide on how to level, or which craft to take for your main. There are frankly better sources for that out there, and the decision is a very personal one. This is an approach that has worked for me, if you are trying to have all of the crafting skills covered and which classes work best with which professions. It requires at keast 5 chars currently, and there will have to be adjustments made when WotLK releases.
Blacksmithing/Jewelcrafting - warrior - A warrior is the choice for this build for a number of reasons. The statues from JC are a viable self-heal (wasted on pallies), and warriors benefit from a lot of the BoP blacksmithing items. Blacksmithing and Jewelcrafting go together so that you are sending ore or metal to just one character (metal for smithing or filligree/settings, ore for prospecting).
Tailoring/Enchanting - Mage/Warlock/Priest - Not re-inventing the wheel here,this build is fairly common. A benefit I have found for multiple crafters is always having a steady supply of things to disenchant to level enchanting. Tailoring is there because, well, they all wear cloth, and having someone to make cloth gear is useful.
Alchemy/Leatherworking(Inscription) - Hunter/Druid - I noticed when leveling leatherworking that a lot of the materials required were potions. Having an alchemist is also benefitial for those quests that require potions (strong trolls blood and frost oil are two that can be dis-proportionally expensive in relation to mats). It also comes in handy being able to transmute your own arcanite, etc. Admittedly, I don't really play leather wearers, so I could probably drop LW and not really miss it, but thats just me.
Engineering/mining or herbalism - Mage - Follow me on this one, a DPS class that can turn invisible, survive a wipe and rez the healer? It has definite benefits. Also making EZ throw dynamite for all your lower level alts is another boon. Honestly, I normally skip engineering because Hunters don't excite me so I don't need scopes, but when I level it, this is the way to go. The gathering profession is a throw in, since I go with a dual gatherer to get mats.
Mining/Skinning - Mage/Paladin/Druid/Rogue (Deathknight?) - You can go one of 2 ways with a gatherer. Stealth through areas killing only those mobs close to the nodes, or AOE kill everything in the area. Take your pic, I've tried it both ways, stealthing can be fun if you like Pvp, when someone from the other faction enters an area with mobs expecting nodes you've already tapped, you can give them a little something to remember you by. Lately I prefer the AOE method.
You can add a hunter with skinning/herbalism if you want, that's up to you. This will get you every crafting profession on 1 server. I used almost this exact setup when I got started on my alliance server, it was pretty successful. However, I discovered I don't much care for the leather wearing classes, so I didnt really need LW & Engineering (why level this if you dont want guns and scopes?).
Mid Afternoon Quickie
6 months ago