Sporeggar is a town found along the western edge of Zangarmarsh, populated by the sporelings. The sporelings are a mostly peaceful race of mushroom-men native to Outland. Players start out Unfriendly with Sporeggar, but can gain reputation quickly.
Unfriendly -> Neutral
Quest [Natural Enemies] - 6x [Bog Lord Tendril] - gives 825 reputation (human bonus), 7500XP (lvl 62). Leads into RRQ [More Tendrils!] - 6x [Bog Lord Tendril]
Quest [The Sporelings' Plight] - 10x [Mature Spore Sac] - 825 rep (human bonus), 7250XP (lvl 62). Leads into RRQ [More Spore Sacs] - 10x [Mature Spore Sac].
Reputation is also given for killing Bog Lords and Fungal Giants - 15 Reputation
Neutral -> Friendly
You can grind Glowcap or Fertile Spores. Glowcap can be found on the ground, Fertile Spores drop off of a good number of mobs in the marsh, typically fen striders and spore bats. However, and this is important, Glowcaps are used to Purchase items from their rep-based vendor. So I'd save those for that specifically, there's some cool items, including alchemical potions, a threat-reducing cape, and a shield that poisons those who hit it.
Friendly -> Honored
There is a Naga kill quest grind from one of the Sporeggarians. These naga also give Cenarion Expedition rep, and there is a Cenarion Refuge quest for their claws which you might want to do at the same time since you're already there.
[Now That We're Still Friends] quest - 12x[Bloodscale Slavedriver] and 12x[Bloodscale Enchatress] slain - 750 rep - repeatable (even it shows as yellow question mark). Does not give any XP at lvl 65.
[More Fertile Spores] quest - 10x[Fertile Spores] - available also at Friendly.
Doing Sporeggar quests (Underbog instance) gives usually 1050 reputation when completed.
At honored, a special escort quest opens up with the Bog Lord Fhwoor, located in Sporeggar. The rewards as of last seen were subpar, but it's fun to escort the oaf. The quest itself is hard, you should at least have a healer to heal fhwoor, who can tank quite adequately most anything that comes his way. The end of the quest forces you to fight an elite and two adds, so be prepared for that.
Honored -> Revered
There is nothing but bog lord grinding. However, the bog lords will stop giving rep at 11999/12000, so save a quest to push you over the edge to revered.
[Now That We're Still Friends] quest still available - 12x[Bloodscale Slavedriver] and 12x[Bloodscale Enchatress] slain - 750 rep - repeatable (even it shows as yellow question mark).
Revered -> Exalted
There is, as of last checked, no means of getting sporereggar rep from revered to exalted.