Also interesting are the following achievements:
You see that first one? "Leading the Cavalry". How would you like to be the first person on your server with that mount? That's impossible right? Maybe not, 75 mounts is quite possible, perhaps not feasible but certainly possible. Once the expansion hits it'll be easier though.
A word of warning however, this is expensive stuff. Also, if you're a tauren you are at a severe disadvantage. Yeh, go cry in a corner hornboy, you won't be the first on your server with this here dragon. Nothing you can do about it except re-roll.
Gold sink? Pretty much. Why else would anyone buy a boat load of mounts if you can only use a single one at a time anyway? The new WotLK mounts have a pretty heavy pricetag as well. 15k for the mammoth, 700g for some of the others. Some are free as different achievement rewards though.
So, we need 75 mounts. Crazy I know, but like the mini pets all mounts are being made into "spells" of a sort and they will no longer take up inventory space. They still do right now though. Lets have a look at WarcraftMounts, a site which has a fairly good list of all the mounts currently in the game.
So, let's make an overview of mounts we can get before WotLK.
That's 36 so far for the horde. 2650g so far.
40 For the alliance so far. An advantage of 4 over the horde...
Also a nice price tag of : 2870g
A blue post sadly informed us the AQ mounts do not count toward the total of this achievement. Not sure about the black one though... But at least the red one has it's own achievement.
There's also several "retired" mounts, but if you don't already have these, you're fresh out of luck to get them now.
Paladins, Warlocks and Deathknights get a summoned mount. I'll not add these to the list right now, but keep them in mind.
For a grand total of:
Taurens and most of the Alliance races will be at a disadvantage however.
If you find any errors or miscalculations, just let me know and I'll edit the list accordingly.
* Wowwiki mounts info section.
* Wowwiki mounts category list.
* Blizzard's official mounts page.
* WarcraftMounts.com. A list of mounts and pictures.
* Wowhead's list of items with a shared cooldown.