Been working on a few personal projects lately and came across a few fairly nerdy tools worth investigating a bit more:

• Bootstrap - "a pack of mixins and variables to be used in conjunction with LESS; a CSS preprocessor." Basically, this is the ability to use variables through your CSS documents, making global changes a lot easier. As long as it is server-side, this seems like a fantastically good idea.
• YUI Scrollview - a Yahoo Developer JS plugin that enables easy touch scrolling within a defined space. What I like about this more than anything else that does the same thing is that it works across browsers much more fluidly. A lot of mobile dev tools are aimed at specific browsers only (i.e. Webkit) and fail to work in other environments; which is a real bummer. I've yet to implement this but I've got a good feeling.
• Corgi Walk Cycle - not so much a nerd tool but something you should consider sneaking into your next site somehow. via Jed via Will.