I know that img body and iframe allow you to add onload= to the tag and have to execute. What other tags support the <
You can also use it on <script> tags except IE where you need onreadystatechange for the same effect.
I think it also works on <object> elements in some browsers (but just a few).
The specs for html4 only mention body and frameset: http://www.w3.org/TR/html4/interact/scripts.html#h-18.2.3
I think it's browser dependent.