Google's site: operator is a lot more powerful than that. You can leave out some components of the address and replace them with asterisks. For example, you can find results from addresses that match this pattern: maps.*.com. Unfortunately, Google doesn't show all the results that match the pattern.
You can also find results that have URLs which start with "news." like "news.cnet.com" or "news.discovery.com". Just search for [site:news.*].
What if you want to search Amazon's international sites? Instead of typing [site:amazon.com OR site:amazon.co.uk OR site:amazon.ca OR site:amazon.de OR site:amazon.fr], just search for [site:amazon.*].
Google's site: operator also works for directories. For example, you can find last year's posts about Gmail by searching for [site:googlesystem.blogspot.com/2012 gmail].
You can even enter URLs that include parameters and leave out the parameters. Here's a way to search the Google Maps help center: [site:support.google.com/maps/bin/answer.py inurl:"hl=en" 3d]. I've used the inurl: operator to restrict the results to English pages, but it's not necessary to do that.
How to restrict the results for [imap] to answers from Google's help centers? Search for: [site:support.google.com/*/answer imap].
These tricks work for image search, as well: