Sketchy Illustrator wireframes
About half of my time as a UI designer goes into making application wireframes that end up in various powerpoint presentations, low-fi prototypes, GUI specs, and User Stories documents. I'm a big fan of sketchy wireframes since they have the advantage of appearing unpolished (so that users and managers do not think they are final), but they also allow the UI designer to accurately depict the application controls, available screen space, and can generally translate well to higher-fidelity designs if needed.
In the past, I've dabbled with various tools to create screen mockups and designs, however, I keep coming back to Illustrator; partly because it's what I'm most comfortable with, but it also fits well into my workflow. Over the past couple of years, I've spent a lot of time creating wireframes, and I've finally gotten around to making a GUI library of sorts - basically just assembling some of the generic controls, windows, and dialogs that are used in the making of the application sketches. So for those of you using .ai to create wireframes, I'm posting a file that will (hopefully) be helpful in future definition and design efforts.
Sketchy Illustrator wireframes (.ai file, 17Mb)
I would also like to credit Gabe Zentall for putting out his GUI Interface Library which I used for many years before eventually building my own...Elements are (somewhat) grouped into layers, as well as symbols. Look for updated versions in the future. Please use as you see fit, credit it appreciated.