Nominative determinism

If you're looking for use cases, I recommend checking out the Gallery or what users are making on our forums.

This is the correct answer :). Monaco 9 if on non-retina and Monaco 10 on retina displays. Though it is a shame there's no bold variant; I'd love to see someone update and create one.

Wow, you're right... I stand corrected.

[nevermind!]

Maybe I'm biased, but check out http://tumult.com/hype/

Hype's raison d'être is making HTML5 animations and interactive content. At a high level, when you have a production tool that is fast and easy to use for this task, it also becomes a great prototyping tool.

A lot of the answer is dependent on what type of prototypes you make. If they require novel animations or complex interactivity, then Hype is a great tool. If it is primarily to string together many different screens, then you may be better served with the other numerous ones out there.

Some specific features:

• Advanced animation system (per-property keyframes, motion paths, customizable multi-point timing functions) but built to be very easy to use with recording
• Composable/reusable parts via Symbols
• Complex behaviors via multiple timelines and timeline binding
• If you are prototyping for the web, you're working in its native format
• Likewise, it is easy to distribute prototypes since Hype exports .html
• Ability to run arbitrary JavaScript for anything Hype can't do

We did some articles a while back on Prototyping with Hype:

• Android L UI Prototyping with Tumult Hype
• Mobile Prototyping for iOS in Tumult Hype
• GUI Kit: Prototyping for OS X Yosemite with Tumult Hype

Of course I recommend using the trial and see if it suits your needs.

FYI - we've submitted to the Mac App Store, so we're just waiting on approval for the release.

Maybe I'm biased, but:

http://tumult.com/hype/