Here's an easy way to have an alternating background color with a Repeater control. There's no "AlternatingItemStyle" like in other data list controls, but this does this trick with a couple lines of code.
protected void OnItemDataBound(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.AlternatingItem)
{
((HtmlTableRow)e.Item.FindControl("Row")).BgColor = "silver";
}
}
