Notice: I've had to temporarily abandon all my projects as I no longer have a running subscription, and I have to make a living. I'm working a summer job in northwestern Ontario which has no internet access, so don't have the option to work on WoW-related things. Sorry. If you would like to pick up this project, send me a private message and I will try to get back to you ASAP. All you would really need to do is convert Simulationcraft APLs to table-object-oriented Lua, but it would be nice to see some code performance enhancements as well.

Versions 6.1.0-7 and up are based on patch 6.1:
• Heavily modified Hunter_SV_T17H.simc
• Hunter_MM_T17M.simc, SimulationCraft git commmit 888238950c10 (March 31, 2015)
• Hunter_BM_T17M.simc, SimulationCraft git commmit 888238950c10 (March 31, 2015)
Versions 6.1.0-1 to 6.1.0-6 are based on patch 6.1:
• Heavily modified Hunter_SV_T17H.simc
• Hunter_MM_T17H.simc, SimulationCraft git commmit rca691378c52c (February 25, 2015)
• Hunter_BM_T17H.simc, SimulationCraft git commmit raeaa96716737 (February 25, 2015)

Basic Resources has a separate command from Shrapnel, it is /bres - not /shrapnel! (commands are separate incase people want to lock or scale one but not the other, or want to run just Basic Resources or just Shrapnel)

Shrapnel is an addon for hunters that simplifies gameplay and maximizes DPS by doing all the decision making for you.
Shrapnel uses an advanced priority list developed by myself and the people over at the SimulationCraft project, improved for ease of use in actual gameplay.
It will calculate which ability would give you the highest DPS during the current combat situation.
The addon is comprised of three main icons, left to right they are:

The Previously Used Ability icon - Displays the last correct ability you used (to show you that you actually used it before the icon changed, can be disabled)
The Best Choice Ability icon - Displays the best ability to use for maximum DPS during the current combat situation
The Cooldown Ability icon - Displays when you should use an ability that is off the global cooldown or has a long cooldown (can be disabled)

Also included are icons for interrupting casts and Steady Focus talent duration.

Other features of Shrapnel includes:

Glowing Ability Buttons - Your ability buttons glow when they become the best choice ability
Multi-Target Modes - Use keybindings to switch between target modes, or have them automatically trigger on spells
Know When You Miss - A red border will appear on the previously used icon when your attack misses or gets parried or dodged
Moveable, Lockable, and Scalable - Each icon can separately be moved to wherever you like on the screen, then locked or scaled to any size
Resource Bars AddOn - No dependencies! Must be enabled within the AddOns menu on the character selection screen

Slash command for Shrapnel user configurable options: /shrapnel or /shr

Basic Resources is an included optional addon to display your focus and global cooldown in a simple and elegant fashion. It also works with other classes, so be sure to disable it for them if you only want it on your hunter.

Slash command for Basic Resources user configurable options: /bres

F.A.Q.

Why is it called Shrapnel?
Dude, I totally named it after my hunter. Can't wait for hunters to take notice in LFG!
Where is it? I don't see it!
Both addons hide themselves when you aren't targetting something you're able to attack. Try selecting a training dummy to move it around and such.
Can I get this addon for other classes?
Smash is available for warriors. Claw is available for feral/bear druids. Assassin is (sort of) available for rogues.