Just making a list of useful buffs etc from quests. Ones I can think offhand:
1. "Friends come in all colours" from Kalec in Azshara. 5 min water walking. This
one can be taken anywhere and cab be reused. (Horde)
2. "By Hook Or By Crook" in the Barrens. Health regen increased by 3% OR +8
melee damage. (Horde)
3 "Rallying Cry of the Dragonslayer" 120 minute buff to melee attack power,
ranged or spell crit for killing Nefarian or Onyxia. Only seems to work for low-level
characters nowadays.
4. "Uther's blessing". +15 crit. This one stacks infinitely if you know how (check my
channel). (Alliance)
5. "The Battle for Andorhal". Ports you from Booty Bay to Western Plaguelands. This
one would have saved me about 50 hours of travelling since I started playing had I
known about it. (Alliance)
6. "Unfortunate measures" Eversong Woods, +5 stamina and spirit for 30 min on
turn-in. (Horde)
7. "Nethergarde Needs You" Ports you from Silthius to Blasted Lands. Note that these
port quests can be reused indefinitely if you never turn them in.
8. "A flash of bronze" Contains an item which ports you to TI.
There must be dozens of others I can't remember. Please add your favourites....