I've gone through a bunch - Illustrator to Balsamiq to Mockflow and now HotGloo. I like Mockflow and HotGloo (both online fee-based apps) because they offer:<p>(1) Master Pages (or at least Master Objects) to keep things DRY
(2) a way for clients to view, navigate, and comment directly on the frames
(3) a good balance: low-fi enough to avoid seeming like a design pass, but hi-fi enough that each object is distinct and recognizable
(4) a good selection of resizable, customizable widgets
(5) an environment separate from the design file. Unlike many, I actually prefer to start from scratch with the design - it frees me from conforming too tightly to the frames, and leaves open the possibility for further iteration. Also, it's handy when passing frames to a visual designer - they can use whatever design tool they like.
Photoshop. I've become so accustomed over the years to the tools/interface, that it's actually faster than pen/paper. Setting it up with common UI elements to drop in quickly makes mockups a breeze.
The most efficient thing for me has been Illustrator w/ wireframe symbols. It's not so low fidelity that I can't envision the end products, additionally I enjoy the control vs. mockup tools like Balsamiq.<p>There some good wireframing resources for Illustrator and other programs in this Smashing Magazine post:
<a href="http://www.smashingmagazine.com/2010/02/05/50-free-ui-and-web-design-wireframing-kits-resources-and-source-files/" rel="nofollow">http://www.smashingmagazine.com/2010/02/05/50-free-ui-and-we...</a>
Google docs, believe it or not. I found a nice wireframing set at the following address:
<a href="http://mortenjust.com/2010/04/19/a-wireframe-kit-for-google-drawings/" rel="nofollow">http://mortenjust.com/2010/04/19/a-wireframe-kit-for-google-...</a>
There're also SketchyPad and iMockups. I've created a list of the tools presented here, you can see it on <a href="http://www.romku.com/list/343849/ui-mockup-tools" rel="nofollow">http://www.romku.com/list/343849/ui-mockup-tools</a>.
Thanks again for all the feedback. I've been trying various tools and i've honestly been loving flairbuilder. Quick, simple to use, and it's highly interactive that's just built in. Haven't tried balsmiq yet but will give it a shot.
as a product manager, I use 2 tools for wireframes and flow design<p>Flairbuilder and OmniGraffle
<a href="http://flairbuilder.com/" rel="nofollow">http://flairbuilder.com/</a>
<a href="http://http://www.omnigroup.com/products/omnigraffle/" rel="nofollow">http://http://www.omnigroup.com/products/omnigraffle/</a><p>The Flairbuilder developer is quite active and responsive about updates. I switched here from Balsamic because Flairbuilder allows for somewhat dynamic & functional mockups.<p><a href="http://twitter.com/#!/flairbuilder" rel="nofollow">http://twitter.com/#!/flairbuilder</a>
I love Pencil for Firefox. It's seriously underrated: <a href="https://addons.mozilla.org/en-US/firefox/addon/pencil/" rel="nofollow">https://addons.mozilla.org/en-US/firefox/addon/pencil/</a>
Omnigraffle, Photoshop or paper. Although, seeing the templates created by Amir Khella (keynotopia.com) has made me want to try to use Fireworks a bit more for this.
Mockingbird - <a href="https://gomockingbird.com/" rel="nofollow">https://gomockingbird.com/</a><p>Maybe it's just because I love web apps done with Cappuccino.