Gridcaster gives some useful add-ons for Grid that are especially useful for casters: SmartCast (one-click buffing), target aggro, unit's target, unit's spell, spellcast bar, Hot/Buff countdown bar, relative position (distance and direction).

New Status

• Target Aggro: shows the threat level (%) of each unit in its target's threat list (useful to know when silly dps is about to pull aggro from a mob that is not being directly tanked). Can be used with the side bar frames or a text frame. In the first screenshot, this is the left bar (showing 100% aggro).
  
• Unit's Target: the unit's target (note that the spell being cast may not be cast on the target e.g. mouseover or focus targets). Can be used by a text frame. In the first screenshot, this is the "Mangy Wolf".
  
• Unit's Spell: spell that is being cast by the unit. Can be used by a text indicator as well as one of the side bar frames (will become the casting bar). In the first screenshot, this is the "Holy Light" as well as the bottom bar.
  
• Smart Cast: Smart Cast for grid (like Healbot's feature). Basically when you are out of combat, it lets you auto-cast the necessary buffs by clicking the same mouse button. Also lets you resurrect a dead player. Once you set it up (e.g. always cast BoW on mages/priests, BoM on warriors etc.), you just need to one-click buff (out of combat). This is useful when joining new parties or in battleground when you don't have time to figure out class and what buff to use. You can use it on yourself when you have to buff yourself with a seal, blessing and aura (and maybe righteous fury).
  
• Relative Position: relative position and distance to yourself. Useful to know when in battleground and you need to chase some someone to heal. Send this to any text indicator.
  
• Buffs/HoTS: some buffs/HoTs can be used with the side bars as countdown bars (like the casting bar)

New Indicator

• Adds 4 side bars (like GridManaBars but you can have 4 at one time). This indicator is not compatible with GridManaBars, which has only one side bar. If you want to use this project please don't use it with the GridManaBars indicator (i.e. under frame -- Mana Bar, make sure all the status are turned off). You can continue to use the Mana status from GridManaBars with any of the side bars. In the screenshot, this is the bar at the top. Each of these can be configured under frame -- advanced -- Side Bars according to the background color and size.
  
  • Side Bar Bottom
    
  • Side Bar Left
    
  • Side Bar Right
    
  • Side Bar Top
    
• Smart Cast Indicator: use only with Smart Cast status. Sending any other kind of status to this indicator will probably cause an error.
  

Instructions for SmartCast

• Send "Smart Cast" status to "Smart Cast Indicator" frame (this is a must). Don't send any other status to "Smart Cast Indicator"...it will probably crash.
  
• Send "Smart Cast" status to "Centre Icon" (set appropriate priority). This is to show which buff needs to be re-cast.
  
• Set up a new macro called GridSmartCast. Bind it to a mouse button (with modifiers if you want) in Clique. The body of the macro doesn't matter as it will be overwritten.
  
• Set up the buffs in "status - smart cast". The options are set up so that you won't override one buff with another (i.e. for buffs that can have only one kind active at a time e.g. aura/shields/blessings).
  When deciding which buffs needs to be applied to whom, the priority order is: named players followed by class followed by raid/party. So if you have 3 mages in your party and one of them wants to be special, you can handle it (set one named party member to one buff, and the rest of the mages/party to another buff. Or individually set them one by one).
  
• There's an option to memorise the buffs that you cast on yourself/other party members so you don't need to set it up manually through the menus.
  
• You can save your profiles for different settings of buffs in different situations (e.g. battleground, questing, tanking, healing, aoeing etc.) This is especially useful for paladins.
  
• When the buff is expired or about to expire (the timing can be adjusted in the settings), the buff icon will appear in Grid if you set it up in the Centre Icon. Use your clique binding to click on the unit frame. It should cast. The second and third screenshots give an example.
  

First screenshot

To summarise the first screenshot:

• top blue bar is mana
  
• top right text is unit's name
  
• left bar is unit's threat level on the target's list (100% in this case)
  
• right side text is target's name
  
• centre text is the spell being cast
  
• bottom bar is the cast bar
  
• red border = aggro level 3 = tanking securely
  

FAQ

Why you might ask do we need to have another aggro indicator?
The left bar shows the unit's threat level on its target list. The red border shows the unit's highest aggro level (1, 2, or 3) on any mob's target list.

Thus for a priest who is healing, it can end up with a red border but nothing on the left bar since it's targeting a character and not a mob.
This new status is not so useful for dps to monitor (who can use Omen to monitor their threat level on their target's list) but for healers and tanks who need to know when one of their silly dps is about to pull aggro (healers get ready their shiny bubble or tanks assist the dps so dps won't pull aggro).

Why is this called GridCaster?
I started writing this project for the spell cast bar then added the 4 side bars when I realised it wasn't compatible with GridManaBars then added threat level but by then I had already created the project so the name sticks.