If you are a web developer, then the communities geared for the tools you use are probably a good place to look. For example, if you are primarily a Wordpress developer then there's lots of Wordpress communities. I'm sure the same goes for whatever your industry your business fits into.

The biggest names in my circle of work tend to post very little at these communities, probably because they are crazy busy. I find the most active participants are either new or hobbyists.

Edit: Perhaps another way to reach out to other big names in your industry is to create "stuff" which can capture their attention. That might be writing code which they might try out or posting info to a weblog which they might read. That's a great way to get your name out there. Conferences are probably another good way.

So, I think you need to dig deeper than web communities.