Here everyone can scan the files for viruses for free and without registering. Here you also can check websites.
It offers you some of the major Web browsers. I also got it when installing Windows 7. I think it's safe.
If you're interested in astronomy, try Stellarium! It's a full-featured free planetarium software. It's safe.
This is a harmful typosquatter. (Update 2015: This site is no longer infected, but still has suspicious content.)
You can share and download free sounds here. It's safe.