My friend recently had his website - http://www.paradisesonline.com/ - completely disappear from the Google (not completely, it still ranks for it's domain name though). It used to be ranking for 'resort getaways' and 'hotels luxury' (in Australia at least). Now it's nowhere to be seen for these terms. It hasn't been blacklisted by the looks of it. Any ideas why this site has been slapped/penalized by Google? Could it have been dodgy link building?
this site has been penalized by Google because of any bad neighbourhood or using any spamming techniques so first update website content and generate quality backlinks.
It didn't get blacklisted because it is still showing a few hundred indexed pages and a PR3. Both would have been reduced to nothing if you were getting blacklisted.
You can fix this by adding much more content to you website, the more relevant documents you create for your "KEYWORD PHRASES", the higher you will rank. It is also possible, that initial backlink boosts for your website kept you higher than you were going to settle.
I have seen your site content, back links, Whois data and also did a site URL search in Google. I find your site pretty OK. If you have relevant blogs then try linking it from there. I find a bunch of low quality directories linking to your site which is just OK. But try and get few good links from relevant site sidebars and navigation bars.