When you export your bookmarks from Chrome and Firefox the resulting HTML looks pretty plain.

Exported Bookmarks with Icons

To enhance the exported bookmarks file by added icons try the following

perl -i'bak' -ple 's/ ICON="([^"]+")>/><img src="$1"> /' bookmarks.html

Enhance with CSS

You can further enhance the file using this js fiddle:
http://jsfiddle.net/vaj0tted/