How to do basic domain name research:

Say you are considering regging this name: WeddingAnniversaries.us

Do a Google search with this search term: "wedding anniversaries". Remember to put the keyword in quotes. On top right you'll see a line saying:
Results 1 - 10 of about 299,000 for "wedding anniversaries". (0.13 seconds)

Therefore your Google score is 299,000.

Next, go to DigitalPoint.com suggestion tool and type in the keywords (without quotes): wedding anniversaries. Choose the market country, normally you would choose the biggest market, i.e. the United States, especially if you're considering regging a .us name.

You'll get both Wordtracker and Overture results. I like the Wordtracker results better because they differentiate between singular/plural and also word order. On the right you see the OVT results, in this case you get about 500 searches/day for the singular and plural terms together. Multiply this by 30 and you get the search count per month, in this case 15,000.

Another important point to check is the value of the advertisers' bids for this search term. For this, go to the Overture bid tool.

Enter the search terms again without quotes. Now you see the highest bid an advertiser is willing to pay to have their ad appear on a page that has these keywords. In this case, it's $0.36.

Next, go to moniker.com or some other provider to check whether the other tld's are taken. In this case, the .com, .org, .info and .net are taken. That's generally a good sign. However, the pages are parked and for sale, and that's generally not a good sign - you've got competition in the market. The more tld's for a given name are functional websites, the better.

So the basic analysis of WeddingAnniversaries.us yields the following results:
Google 299,000
OVT 15,000
Wordtracker 7,500
Advertiser highest bid: $0.36
Taken in .com, .net, .org, .info

Clearly a nice name, worth regging at least in the .com extension. Maybe not in the .us extension, but I think .us would be much better than .net or .org in this case.

You should do this basic analysis for each domain name you consider regging. It gives you time to reflect, and some hard data to back up your decision.

If you're out of ideas, you can find premeditated, available domain names at DomainBeta.com - good available domain names, or you can check which domains are just about to expire on DailyDropped.com - Expiring Domain Names. They're both my sites, so quality is guaranteed