There are various ways to "cover" eggs with polymer clay, and many different looks that can be achieved!
This page at my site has lessons, examples, troubleshooting, etc.,
for all the things below (as well as which
plastic eggs work, etc.):http://www.glassattic.com/polymer/eggs.htm
The eggs used can be real eggs which have been blown out, or they can be certain types of plastic eggs (usually available just before Easter). Wood or papier mache eggs can be covered too.
The eggs can be any size, and real eggs can even be "partially" covered then soaked overnight in strong vinegar to dissolve the shell leaving behind a hollow egg shape of clay with empty areas in the design.
Clay covered eggs can be used in various ways too, as:
...xmas tree ornaments
...rattles (with seed beads, etc., inside)
...boxes, possibly hinged
..."bodies" for sculpts
They can also:
...have "feet" or other parts added to them
...be turned into baskets (possibly adding handle, or just used as a form)
...sit in "stands" made from polymer clay or other things
...just sit around in a group in a bowl for decorative display
HippieKinder posted two covered eggs in the Completed Projects
...and there may be others that have been posted at Craftster too.
She used two techniques for covering the surface of the egg --sheets of stripey clay (from leftover canes?), and Balinese Filigree highlighted heavily with several colors of mica powder (Bal.Filigree in polymer clay is the technique of onlaying spirals and other shapes of thin "ropes" of clay onto a clay surface of other clay or onto another material...other manipulations are possible too).
And here are a few more I've found:
Balinese Filigree and cane slices, by CozmicStardusthttp://www.craftster.org/forum/index.php?topic=236601.msg2594268#msg2594268
cane slices with sculpted flower on top and ring stand underneath, by __themidgehttp://www.craftster.org/forum/index.php?topic=236577.msg2593964#msg2593964