This post is for bloggers and small businesses that want to make themselves more accessible than most and perhaps impress their readers.  To make this work, you will need

• A Google Talk account (gChat within Gmail is fine)
• A web publisher that allows you to insert custom HTML.  I have done what follows with Weebly and Wordpress, although I imagine Posterous and other publishers allow you to do so as well.

Next,

1. Visit http://www.google.com/talk/service/badge/New (link opens new window) to generate your custom created code.  Copy it.
   
2. Paste this into a web editor's "custom html" box.
3. Enjoy instant accessibility
   

Just like that, you've got a Google Chat button that allows web visitors to instantly message you as a "Guest" without signing up for Google Chat or any other messenger.  As the poster, you will not know who your reader is since they have not logged in to any accounts.  Likewise, your reader will not know your email address.  The benefit here is inspiring potential customers or readers to reach out when they otherwise might not.

I recognize this technique is more advanced than some other postings but still consider it "intermediate" in that you only need to copy and paste code, not write your own.

UPDATE 10/4/2010: Feedback on this one is coming in fast and furious.  Thanks to Ryan U. for bringing this Google VOICE widget to my attention.