Just follow these steps to enable anonymous access to your sharepoint 2010 site.
Open SharePoint Central Adminsitration. Under Application management tab, Click on Web Application management.
Choose your web application and click on ‘Authentication Providers’ link on the ribbon.
Under ‘Zone’, Click on ‘Default’.
Tick ‘Enable Anonymous access’ checkbox and click on Save.
Go back to WebApplication link and click on ‘Anonymous policy’ link on the ribbon.
Under ‘Anonymous user policy’, just check ‘None’ and click Save.
Go to Top level site of your site collection. Navigate to Site Actions -> Site Permissions.
Click on ‘Anonymous access’ lilnk on the ribbon.
Check ‘Entire website’ option and click OK.
All done !!