You can use URL Rewrite to generate friendly URLs for search engines or simply to redirect a user to a certain page on your site.
In IIS7.5 (and also applicable to IIS7) you can achieve this by installing the URL Rewrite Module, the download can be obtained from www.iis.net/extensions.

Steps to set your start homepage e.g. http://localhost/ to point to http://localhost/mynewcustomhomepage.aspx
1. Add a new rewrite map via "View Rewrite Maps..." -> "Add Rewrite Map..."
- Give your new mapping entry any name and enter Original value as / and the new value as mynewcustomhomepage.aspx
2. Add a new rule, selecting the template "Rule with rewrite map", select OK then choose rule action as Rewrite and the rewrite map as the one entered in step 1 above.
3. Click OK and now when you navigate to http://localhost you will be directed to http://localhost/mynewcustomhomepage.aspx
The other useful rule is the User friendly URL template. This allows you to map URL with querystrings to absolute paths e.g. http://www.example.com/default.aspx?a=apple -> http://www.example.com/a/apple/
The "Create corresponding redirect rule" is for specifying whether or not you want users to be able to use the rule to access your absolute path by entering querystring (internal URL) or only by entering absolute paths.