(May be very out of date. If you'd like to volunteer to update it, let me know.)

* /qh help
Lists all the QuestHelper slash commands.
** /qh help "command"
Tells you about a specific command.
* /qh settings
Opens the Settings menu at the current cursor location. Note that not all settings can be changed through the menu.
* /qh track
disables/enables QuestHelper's Quest Tracker, which provides status on your nearest objectives, in place of the default Tracker.
* /qh hidden
Displays a list of all the hidden objectives, why they are hidden, and depending on the reason, will allow you to unhide them.
* /qh ftime
Toggles the display of the flight time estimates.
* /qh locale "locale"
Sets the locale to use for displayed text., or lists possible locales if no argument is given.
Defaults to your client's locale the first time you run QuestHelper. The only locale that is complete right now is "'enUS"'. Missing translations will be marked with red text.
* /qh share
Toggles objective sharing on and off. When on, will share quest objectives and progress with other party members that are using QuestHelper 0.17 or higher, and also have sharing enabled.
* /qh solo
Will disable quest sharing and ignore anyone you might be partied with, basically assume you will receive no aid from your party members.
* /qh comm
Toggles the display of the data sent between peers. I use this for debugging, but some people just love to stare at streams of meaningless data. It's really quite hypnotic. . .
* /qh hide
Hides QuestHelper's minimap arrow and World Map icons and paths, and suspends the calculation of routes.
* /qh cartwp
Toggles using Cartographer Waypoints to display your current objective.
* /qh tomtom
Toggles using TomTom to display waypoints for your current objective.
* /qh button
Toggles the QuestHelper button on the World Map frame.
* /qh level "offset"
Sets the level offset used by the level filter. Can be positive or negative. Invoke with no arguments to see the current offset and your effective level at various party sizes.
** /qh level 0
Only show quests at or below your own level.
** /qh level +2
Show quests up to two levels above your own level. This is the default.
* /qh nag
Prints counts of all the new or updated quests, objectives, etc, that you have found that aren't in the supplied database.
Note: To reduce memory usage, QuestHelper deletes static quest data that doesn't belong to your faction. So, if you play both sides, it will always think the quests you did for the opposite faction are new.
** /qh nag verbose
Displays the specific differences between your data and the static data.
* /qh find "category" "query"
Allows you to create custom objectives by searching for known items, NPCs, and locations. The queries allow fuzzy string matching, and so should happly accept typos and partial matches.
Note that if you attempt to create an objective twice, it will instead hide it.
** /qh find item "item-name"
Search for items.
** /qh find npc "npc-name"
Search for NPCs or monsters.
** /qh find loc "zone-name" "x" "y"
Search for a location in a zone. You may also use a comma, should you feel the need to.
** /qh find loc "x" "y"
Search for a location in your current zone.
** /qh find "search-string"
Searches in all categories.
** /qh find
Invoking the find command without any arguments will instead display all your current user created objectives, allowing you to easily turn them off.
* /qh filter "filter-name"
Toggles objective filters on or off.
** /qh filter level
Shows or hides objective that you probably can't do. Note that this considers the the levels of everyone in your party, not just you. If you're partied with somebody higher than you, it might not hide a quest that it otherwise would have.
** /qh filter zone
Shows or hides objective that aren't in your current zone.
** /qh filter done
Shows or hides quests that aren't complete.
** /qh filter blocked
Shows or hides objectives that are blocked, i.e. require something else to be done first, such as turn-ins for incomplete quests.
* /qh scale "value"
Scales the map icons by this amount of their default size. Will accept a number or a percentage, in the range of 50-300%.
* /qh perf "value"
Scales the CPU workload for QuestHelper's route calculation routine. Will accept a numbere or a percentage, in the range 10-500% (although we don't recommend going above 100%).
* /qh recalc
Recreates the world graph and location and distance information for the active objectives. You probably don't need to worry about this.
* /qh purge
Deletes all your collected data. I'd prefer if you avoided using this any time other than immediately after sharing your collected data.
Requires that you to enter a randomly generated 8 character case sensitive alphanumeric password, to hopefully ensure that people read the message that gets displayed.
* /questhelper
Alias for /qh.
* /find, /qhfind, 
Alias for /qh find.
* /qh find monster
Alias for /qh find npc.
* /qh find location
Alias for /qh find loc.