How can you make sure your web address is remembered when you read it out? Get a short URL. A web address that's easy to say and easy to remember.
It's easy to register short domain names such as .fm and .co using a domain registrar such as GoDaddy: http://jngl.es/godaddy
Plugins I recommend that will allow you to redirect your short web addresses include Pretty Link Lite and YOURLS.
Pretty Link Lite: http://wordpress.org/extend/plugins/pretty-link/
YOURLS: http://yourls.org/
Remember to say any web address that you'd like your listener to remember at least twice.