Rest - fully restores HP and MP
Random Encounter - Puts you in a fight from the Random Adventure list
Log Out - Logs you Out
Return to Town - Takes you back to Granemor

Update the Void - Not really needed anymore, but it was used back when the void held launch night monsters as they'd rotate in and out every few minutes.

Fight! - Takes you to battle the current Void Monster.

The void removes guests, but it has been know to be used for testing some such as:
Guardian Angel
Petey the Parrot
Water Witch
Pygmy Zombie Entourage
Sparky
Stunflower
Bunny

HISTORY OF VOID MONSTERS
Yeti
Soldier Wasp
Grizzle
Minotaur
Young Minotaur
Ziragat
Akriloth
Kresh
Ultra Magma Akriloth, Dragon
Frogzard (Terrorzard)
VorpalZard
Sphinx
Creech
Gargel
Chimera
Lectro
Moonray
Giant Nautilus
Behemoth
Skeeter
Garganth
Grunt
Sea Titan
Ultra Giant
Drakel Power Armor
Drakath, the Undead Dragon
Serlissa the Water Dragon
Night Terror
Krenos the Energy Dragon
Zarlath
Sunray
Ruby Golem
Quizzat
Altidont
The Roc
Grizzle
Berserker
Worm Caster
Dracolich Rider, Undead Dragon Rider
Hellzard (Now Infernozard)
Whalezard
Cloudzard
Nightzard
Lightzard
Toadzard
BlizZard
Storm Zard
Sand Shark
Sir Pwnsalot
Thrachee
Vorteks (Now Mummicane)
The Sorceress
Drakel Water Raider
Gigaworm
Velociraider Rex
Jackel Sano
Fenris
Drakel War Party
Ultra Akriloth, Dragon
The Reaper
Frogzard
Xyfrag
Hybee Scout
Famed Fighters
Veegus
Undead Terror
Valencia
Robina
Skull Ape (Undead)
Voracious Were-Hare
Stragath and Stragath's Head
Xarymandias
Varnak
Giind (Megdragon)
Shirrig
Battle Whale
New Halenro
Drakonnan
Rock Man
Knight
Tank Knight
Commander Kragg
Captain Frolgar's Braken
Fear Drake (dragon)
Soralag Drakel/Dragon Hybrid
Algern the Shadowknight
Hirroo
Carnax
Giant Mummy
Flibbitiestgibbest
Klubber, the Undead Dude
Zlok
Syphon Vamp
Banshee Messnger
Night Horror
It's You!
Orc Horde
Dire Shadow Dweezel, Dragon

CURRENT
Nightbane

Thanks to 1wingangel, chrislongden3 and Lady Tomo
If you know of any missing monsters, or monsters that need to be removed from the list, post in encyclopedic discussion.

Source

Suikoman444, http://forums2.battleon.com/f/tm.asp?m=3717858