GummiBears
If you like your bears sticky, you want GummiBears.
The Problem
By default, hitting an action button that has a spell on it (say Tranquility) while in bear or cat form will cause you to shift back to caster form so that you can cast it. More than once a clumsy paw of mine hitting the wrong button has dropped me out of bear form while tanking; never a good thing.
The Workaround
There is a console variable (aka a CVar), autoUnshift, which can be set to 0 to change the games behavior so that the game will throw an error rather than unshift you when this happens. The only problem is that this CVar is account wide, not per character. So, for example, with that CVar changed my shaman has to first exit out of Ghost Wolf form to cast a spell which is annoying.
The Solution
What this addon does is manage that CVar setting for you. Whenever you shift into bear form, the CVar is set so that spells won't cause an unshift. At all other times the setting is returned to the default behavior.
I installed this addon and decided I didn't like it, but unfortunately this addon somehow messes with your cvar settings to where even if you uninstall it, it doesn't stop working. I had to reset my cvar settings and get my backups of my WTF and interface folders to sync to the servers again and it's been a huge pain. So, fair warning to anyone who decides to use this and ends up not liking it like me.
Ha har... What once was an annoyance is now a problem... back in my day, we had to pre-pend every spell in macros with /cancelform... uphills... both ways... in the snow... with barb wire on my hooves for traction.