Hello,
I have been undertaking a lot of offsite SEO content development and
link building. I noticed in Webmaster Tools that my site, had last been crawled April 10, 2008. I believed it should have been crawled more recently and so took that date (over 15 days ago) as a signal something might be wrong.

Thinking something was wrong with my site not having been crawled in
over 2 weeks, I researched in Webmaster Tools. Here's the shocking
discovery I found, that probably had a "duplicate content" impact on
my site.

What I found was this: under the "Pages with External Links," other domains that I had from the same hosting company were pointing to my main site. And, by pointing at this site, since apparently the Google spiders don't distinguish from separate IP addresses (the IP address from the pointing sites had no content), it probably looked like duplicate content. SHOCKER!

Here are my questions, can someone lend their knowledge:
So, if my description was clear enough or made sense:
1. I believe that this might have created a "duplicate content"
condition and caused the spiders to ignore my main site. Can someone
discuss?
2. I have now parked those other pointing domains. Does this sound
like the right fix?
3. How do you tell if your site is listed or is ignored as "duplicate content?"
4. How do I get my site "crawled" and indexed again if it did look like duplicate content?

Please discuss,
Thank you!

Here's a good site that gives an in-depth explanation on duplicate content:

http://www.seroundtable.com/archives/013057.html

What I've read, though, is just focus on inbound links, since that probably outweighs everything else. Adding some to your signature helps too .