The point of this thread is to be a comprehensive summary of the available javascript libraries - but with a twist.

Most threads I've seen thus far with regards to libraries are:
  1. Which one is the 'best' ?
  2. Poll: Which library to you prefer and why?
  3. Here's a quick breakdown of all the libraries

Inevitably, responses to these threads are short "jQuery rulz" or "Prototype is too big" or "You can't forget Mootools" responses that end up falling short of what the OP is typically looking for.

Let's break out of the mold and make this thread different. Each response should contain a comprehensive summary of the poster's experiences with their favorite library. Try to include things like:
  1. Which library are you *currently* using for your project?
  2. What other libraries did you consider and what made you decide on Library X?
  3. What problems/successes did you experience with Library X as part of your implementation?
  4. What are your recommendations for someone trying to decide on a library with regards to library X?

That should be a good list to work from, but is by no means complete. As the thread gets bigger, I'm certain we'll end up with a huge compendium of solid, real-world experiences for just about all of the libraries out there!

I'll post the first response to demonstrate what I mean. Hopefully this can become a good resource for people new to the world of javascript libraries and possibly point them in the right direction in making a choice.