I have a lot of dialogue practice on my English For Beginners page under Audio Conversations.
However, I have the best sites for simple and basic conversations on my English Themes For Beginners page under Conversations. I recently added a link called Flash Conversations at the bottom of that category. It has quite a few nice examples of audio, text, and animation supported dialogue.
This post was really helpful to me–thank you! I am currently tutoring ESL for an independent study in my MA English program. Please feel free to check out my blog: your thoughts would be really appreciated! http://www.youridentity.wordpress.com