There are many colors and styles available. You can go for a slight change or you can go for something very dramatic. If you have light colored eyes, then you will have one set of colored contacts available to you called enhancement color lenses. And if you have darker colored eyes, then you will have a different set of colors to choose from called opaque color lenses. The most popular brand is probably Acuvue, namely their Acuvue 2 Colors Opaques and Acuvue 2 Colors Enhancers lenses.
The colors available now are much better and much more realistic looking than contact lenses available just a few years ago, so now is a great time to try them.
Is a Prescription Needed?
Even if you don't wear contact lenses, you can still get colored contacts since you do not need a prescription. You can just set the power level to "0" which means there will be no vision correction with those contacts. Since contact lenses are considered medical devices, you will need to see an eye doctor if you do plan to wear non-corrective colored contacts. Do not buy colored contacts from a website that does not require a prescription or ones that offer colored contacts without prescription - it's actually the law that you do need a prescription.
More Information About Non Corrective Colored Contacts:
Name Brand or Cheap Colored Contacts?
Some of the most popular brands of colored contacts are by manufacturers like Acuvue 2 Colors, Durasoft Colors and Freshlook. It's best to go with a name brand for the safety of your eyes. Cheap colored contact lenses are just that - cheap. You wouldn't want a cheap heart transplant, right? Some of these cheap brands are made of cheap materials. They can be very uncomfortable to wear, causing stress and strain on your eyes and can even cause a serious eye infection or worse. If you're going to go cheap, get some cheap blue jeans - not cheap contacts.
Am I More at Risk for an Eye Infection?
Honestly, yes. Anyone wearing contact lenses is more at risk for an eye infection. This is because you are purposely putting something in your eyes. What you put in them needs to be clean and free of any foreign objects. Proper contact lens care will significantly bring down that risk.
Learn More
If you're interested in finding out more about non prescription colored contacts, then get a lot of good information that can help educate yourself at the Free Contact Lenses Guide.