Your kids will love them.  Your more advanced students may already know how to cut and paste into their page's code.  If not, I'll bet you have at least a few students that will teach them, or else they'll figure it out.  All of the instructions are right there.  Let them do it and see what they can come up with.

One word of caution?  Make sure that your students keep marketing at the forefront.  Some of these scripts are very cool but also very useless!  Don't let it turn into a game for them.  Make them justify each script to you before they actually place it on their page.  There are many Javascript pages available, but the site I found that also included the best directions is:

Net Mechanic - This is a magnificent tool that your students can and should utilize for every page that they create.  However, the detail you ask your students to report on can vary from student to student (or you can have advanced students run reports for your methodical students).  Net Mechanic is an online tool that will analyze your (or any existing) Web site.  It will check it and offer detailed reports for many categories.  Pay special attention to the one that talks about fast loading pages.  This will provide you the opportunity to have your page "tested."  It's what I'll be using to measure the size of your pages for your project.  Be sure and use it!

TIP: To place a URL into Net Mechanic, don't attempt to type it in!  Open the page you want to check in a second browser window, then double-click on the URL in the location bar until it is highlighted.  Once highlighted, use the keystroke CTRL+C to copy the URL.  Then go back to Net Mechanic and use the CTRL+V keystroke to paste the URL into the dialogue box.   This eliminates the possibility of typing the URL incorrectly.