A simple Chrome extension that lets you disable/enable images on "per host" level.
Click once and you'll disable images for the current site. Click again and images will be re-enabled.
There are some options available, but basically, the extension does just that (and nothing more)
Questions & Answers:
When you disable images on the current site, all the images on the currently opened page are already loaded. The refresh will force the browser to hide them.
When you re-enable images, you will need to reload the current page in order for browser to download and show you these images.
If you don't like this behavior, go to the "Options" page and uncheck the "auto-refresh" checkbox.
The extension doesn't have this option itself, but it should be easy to do it with few clicks:
1) Go to Chrome content settings -- just type "chrome://settings/content" (without the quotes) in the URL box and click "Enter"
2) Select "Do not show images" and click "Done"
Now, it will disable images by default for all sites. When you want to enable images on the currently opened site, click the "Images On/Off" icon.