There's a July 2003 article at about moving items from an Available List to a Selected List here:

(Sorry, I looked on SitePoint for a similar article first but couldn't find one).

It works fine when the lists are on the same page but when I implement the two lists in different frames, it works in Mozilla but not IE 6. I run the script from where the frameset is declared, so I "get" the selected list by

selectedList = window.selected.document.getElementById("selectedOptions");
availableList is similar except its in an "available" frame. However, IE doesn't like it when it gets to the following line in the code:

Anyone know why IE is acting this way?