This plugin has native Joomla 1.5 and 1.6 support.
It displays simple scroll to top button. Just install and publish the plugin and you'll see a button right after your content.
1. You can define position of button - before, after the content and at the right bottom corner of your browser.
2. You can use both jQuery and simple #top method without script linking.
3. You can vary speed of smoothing.
4. Not spoil XHTML 1.0 Transitional valid pages.
And this plugin is absolutely free!
You can download the plugin from it permanent page: http://union-d.ru/dev/node/2