Below is a list of the various quests that have you visit the graves of the notable and lesser known heroes:
A Daughter's Love -- The last step of the Mor'Ladim quest chain in Duskwood, you place a ring on the grave of Morgan Ladimore, a hero of the Alliance who returned home only to find his wife and nearly everyone he cared about dead.
Of Forgotten Memories -- Part of the Tirion Fordring quest chain in Eastern Plaguelands, you visit Fordring's false grave to retrieve the toy hammer his son left there in remembrance.
Sully Balloo's Letter -- The beginning of a quest that prompts Magni Bronzebeard to build a memorial to Sully Balloo, a soldier who fell defending the Thandol Span joining Lordaeron to Khaz Modan.
Peace at Last -- The end of the Shadyrest Inn quest chain in Dustwallow Marsh, you lay a wreath on the graves of the Hyal family who were killed by marauding Grimtotem tauren. (Pictured above)
A Strange Historian -- A step of the very emotional Pamela Redpath quest chain, Chromie sends you to search Joseph Redpath's grave for his wedding ring to help redeem his soul.
Fallen Hero of the Horde -- An orc ghost on the border of the Swamp of Sorrows and Blasted Lands sends you on a series of quests to free the souls of his brother warriors.
For Love Eternal -- Not exactly visiting a grave, but you visit the haunted ruins of Darkshore to free the wandering spirit of Anaya Dawnrunner for her husband Cerellean Whiteclaw.
Tomb of the Lightbringer -- You escort the Anchorite Truuen to the tomb of Uther Lightbringer in the Western Plaguelands so that he may pay his respects to the great paladin.
Until Death Do Us Part -- A forsaken in Thunder Bluff sends you to place her pendant on the grave of her husband Yuriv in Silverpine Forest.
Meet at the Grave -- A part of a long quest to learn the secrets of Linken's past, you have to die
And while you can't pick up these quests for a few months, it's worth remembering:
Honoring a Hero/Honoring a Hero -- Bring an offering to remember Grom Hellscream and Uther Lightbringer, respectively.
So what quests will you be using to help remember those who have gone before?