Add Blocks
breadcrumbs
cart_sidebar
catalog.compare.sidebar
checkout.cart.coupon
currency
left.newsletter
catalog.leftnav
paypal.partner.left.logo
paypal.partner.right.logo
right.reports.product.viewed
sale.reorder.sidebar
checkout.cart.shipping
tags_popular
wishlist_sidebar
right.reports.product.compared
wishlist_link
<block type="core/template" name="test" template="at.phtml" before="-"></block>
<!--Example-->
<reference name="left">
<block type="core/template" name="test" template="at.phtml" after="tags_popular"></block>
</reference>
<!-- Add CMS Block -->
<reference name="left">
<block type="cms/block" name="services_sidebar">
<action method="setBlockId"><id>new-arrivals</id></action>
</block>
</reference>