Question: How can I add an icon to my Rails application (to show in tabs when opened in a browser, etc.)?

Answer: 
You're talking about a `favicon`.

Add this in the `head` part of your layout:

```
<link rel="shortcut icon" href="/path_to_your_pic"/>

```
Put the `favicon.ico` under your `public/` folder and then add `<%= favicon_link_tag '/favicon.ico' %>` to your `<head></head>`

Then if you try it and doesn't work out, even after you cleaning browser's cache, you should try run the server at a different port. By default, rails runs the server at port 3000. 

Try changing the port to something you haven’t used before – run the app as:

RAILS 3: rails server -p 12345

RAILS 1/2: ruby script/server -p 12345