Thanks to Jeff Howden there is now a bookmarklet for Mozilla/Netscape (tested with Mozilla 1.1). To use this, add it to your personal toolbar and then when you are on a page that you want to add as a Sidebar, just click on the button on the toolbar. (NOTE: Adding sidebars may work better if you have the Sidebar panel open, so you may want to press F9 before trying the bookmarklet).
Notice for Opera Users: This will not work for Opera, but Opera does not need it since Opera has a built-in feature to add any page as a Panel. Simply open the Hotlist and right click and you will see an option for “Add Panel”.
To Install/Use: Do not click this link, but drag it to your Personal Bar (View > Show/Hide > Personal Toolbar):
Mozilla AddAsSidebar Bookmarklet
The bookmarklets here for TV Guide, IMDB and MRQE were inspired by the Google bookmarklet at Bookmarklets.com. They are all variations on that same theme.
Please note: The TV Guide website uses a cookie to remember your zip code and TV provider. You will only need to set that once if you allow cookies.
They are snippets of javascript code which give you shortcuts to Internet tools. They are also called favelets. See bookmarklets.com for lots of very cool examples of bookmarklets.