This script (originally by Iccii) implements the effects: add border, bevel and emboss, color overlay, drop shadow, gradient overlay, inner glow, inner shadow, outer glow, pattern overlay, satin.
It works when applied on a (transparent) layer or on a textlayer, but not on the background-layer . The layers are linked so the object can be moved around.
The latest version is tested on GIMP 2.4.
See webpage with examples http://users.telenet.be/ev1/gimplayereffects_en.html