Is there any good alternative to Microsoft Visio (for the PC)?

I’ve been using Visio as almost my exclusive tool for almost a year now, and I have to say that while it does a decent job at creating Information Architecture Documents, it still has MANY flaws that repeatedly drive me nuts. The interface is clunky at times, and making selections can be a frickin’ nightmare on complex drawings. Worse, trying to associate shapes – despite Microsoft’s help section, forums and trite answers to the contrary – is often a morass of complex equations, shapesheet editing and hair-pulling when it STILL doesn’t work like it should. So, a co-worker and I were discussing it the other day, along with a host of other things, and started to wonder: why hasn’t Adobe come up with an analog to Visio? Illustrator gives you the flexibility you need in terms of creating shapes, using layers (Visio’s use of ‘layers’ is rudimentary and – dare I say – retarded) and of course tools to make it LOOK good. But Illustrator isn’t a good IA tool because it doesn’t have the same finesse that Visio does when it comes to associating shapes in the manner needed – or at least is easiest – for IA work.

I know that a lot of Mac users swear by Omnigraffle, and I’ve heard it’s a great tool. Unfortunately, since I’m on a PC at home and away, that’s not an option. But from what I can see, aside from a few 3rd-party programs that really pale in comparison to Visio, there really isn’t a qualified alternative. Having looked at Visio 2007 and tested it out online, I think that while they have made some good improvements, I also see some things that seem to go in the exact WRONG direction for what I need the program to do (of course, that is one user’s needs, so take it with a pound of salt).

So, back to Adobe – how cool would it be to be able to integrate a Visio-like program that pulls in content from disparate sources in much the same way that InDesign does with Illustrator, Photoshop and certain other tools. Again, Visio 2007 shows the ability to integrate data sources from Word documents, Excel files and even databases, but I’m not sure how much that will help when I still can’t copy a frickin’ page or have a shape update on multiple pages when I change the source (a la Smart Objects in Adobe products).

That being said, ARE there any other alternatives? And who would we have to bribe to get Adobe to create a tool that matches (and exceeds) Visio? Or even – is there a good way to make Illustrator a little simpler so that IT can act as a substitute?

Update

After doing some looking around, and getting some response, I found a few programs and links that are interesting.  First, Boxes and Arrows does some of the leg work in finding a couple of Visio replacements (Visio Replacement? You Be the Judge and Keeping Pace with Change).

and then I found a few links courtesy of the recent IxDA threads:

Denim – a visual design tool for tablet PCs (or conceivably, Wacom pads) that acts as a hand-drawn prototyper.
Axure – a more professional tool that seems to have the basics for rapid prototyping but is probably not quite powerful enough – or polished enough (IMHO).

And of course, Adobe Flex seems to be getting a LOT of attention – and seems to be heading in a great direction as a rapid prototyping tool for rich interaction apps.