Just wondering what software you utilize to produce a visual sitemap / site structure representation before you begin large sites?

I'm searching to pre-plan a sizable site, but cannot find worthwhile software that helped me to map the website aesthetically (As well as in pages/groups)..

I strongly suggest considering it: http://world wide web.balsamiq.com/items/mockups

The Balsamiq tool is right for doing mockups (i suppose this is exactly what you're mentioning too when speaking about sitemaps before you begin...). With this particular software you are able to rapidly generate a functional wireframe of the items ever you're creating. A lot functionality that you could really share it together with your client to find some good sign offs just before typing the very first little bit of code.

Very effective!

And also the other one...just proven in the last MIX09 is SketchFlow. Could not remember it in order to save my existence. This can be a WAY Awesome tool for sitemaps and UI mock up. I had been looking for the actual MIX presentation because it is super awesome to look at. But here are a few YouTube videos of this presentation from the user perspective I suppose.

http://world wide web.youtube.com/watch?v=zsAZjb7FKXA

http://world wide web.youtube.com/watch?v=f3ErrS68YMM

Take a look!

update...found the SketchFlow video!!! http://videos.visitmix.com/MIX09/C01F

Great keynote after that too: http://videos.visitmix.com/MIX09/KEY01