Align image in the center over avatar.

[LifesGreatestGift]

<div class="memberavatar">
    <code for actual avatar image a href and img src />
    <second image class="memberavatarimg" />
</div>

<style type="text/css">
.memberavatar{position:relative;margin:0 auto}
img.memberavatarimg{position:absolute;bottom:4px;right:4px}
</style>

you need to add a div around the avatar, and position it relative so that you can then position the (second) image absolute over the avatar

this is a general guide, feel free to edit as you see fit.