there was a while when i made a circuit of southshore and stormwind before every raid for combat pots and ice threaded arrows. i finally broke down and picked up a boatload of thorium and dense stones and went through the miserable process of making tons of thorium arrows and mailing them all to an alt. i tend to make about 100 stacks when i do this now, and i've already gone through it a few times :-/

Poisons (1-2 stacks of each, sometimes 3 of IP6), major health pots, greater agi pots (I'm too cheap for Mongoose, generally, and if we're really close, we have a guild stock of Mongoose that gets passed around anyway), stashed resist pots for appropriate fights, 2-4 stacks of Heavy Runecloth Bandages, sharpening stones if I happen to have any on hand.

As Warlock i bring in Naxx: Major Healing Potion x 20 , Greater Arcane Elixir x 10, Elixir of Shadow Power x 10, Flask Of Supreme Power x 2, Brilliant Wizard Oil x 10, Heavy Runecloth Bandage x 50, Greater Nature Protection Potion x 20, Greater Fire Protection Potion x 10, Windblossom Berries x 40.

Special on Patchwerk: Mageblood Potion x 5, Major Troll's Blood Potion x 5, Nightfin Soup x 5, Demonic Rune x 5

Fixed :)

On a more serious note, I normally bring :
30 Major Mana
20-40 Dark Runes
10-15 Protection Potions (depending the instance / encounters)
10 Charges of Lesser Mana Oil
10 Charges of Brilliant Mana Oil (sometimes 20 depending on the fight / night / # of attempts expected, especially now that they don't persist through zoning again)
20 Mageblood
20 Elixir of Fortitude
5 Combat Mana / Healing
Sagefish Delight / Nightfin Soup
Stack of Heavy Runecloth Bandages
Couple Dirge's if I have some extra.
and most importantly, at least 4-5 Stacks of noggenfogger ^_^.

Consumables take up more of my bag space than anything else, but it's better to be over prepared ;)

As a rogue, I always like to have on me:

10 x major heal pots
40 x heavy runecloth bandages
200 x thorium arrows
20 x each type of poison (might up this to 40 instant since the zoning fix was unfixed)

And some mixture of:

winterfall firewater
juju power
greater agility and/or mongoose pots
smoked desert dumplings
tender wolf steaks / spider sausages

Anything other than that is specifics for specific fights.

Nobody is going to bitch about the oversize, goofy sig?

Juju Power!
Firewaters
Dense Sharpening Stones
Elemental Sharpening Stones
Major Healing Pots
Combat Healing Pots
Felwood Stamina Food
Gordok Green Gog
Mongooses (when i can get hold of them :( )
Any cheap scrolls on AH (bargains!)
Yarr!!

But then again I haven't got to use any of the DPS consumables in AQ yet because we're only upto Fankriss :( Damn multi tank encounters!

I currently have a bag with the following in:
5 Major Health
5 Major Mana
5 Mageblood
5 Greater Arcane Elixir
5 Elixir of Greater Firepower
5 Nature Protection
5 Frost Protection
5 Greater Nature Protection
5 Greater Frost Protection
5 Greater Fire Protection
5 Greater Arcane Protection
5 Greater Shadow Protection
7 Blessed Wizard Oil
7 Powerful Anti Venom
3 Wind Blossom Berries (will replace with something useful once I've used them up - probably Nightfin Soup)
4 Night Dragon's Breath (will replace with something useful once I've used them up - probably Monster Omelette)

I'll take more health/mana/protection pots depending on encounters. In general I rarely use any potions though.