Check out these big 10mm common cathode through-hole LEDs! The opaque epoxy package causes these LEDs to have a soft, diffuse glow.
Diffused LED - RGB 10mm from MindKits New Zealand
LEDs and Illumination - SparkFun Electronics
LED Mixed Bag - 10mm - COM-11459 - SparkFun Electronics
Diffused LED - RGB 10mm - COM-11120 - SparkFun Electronics
COM-11120 SparkFun Electronics, Optoelectronics
Diffused LED - Blue 10mm - COM-10635 - SparkFun Electronics
Diffused LED - Blue 10mm - COM-10635 - SparkFun Electronics
LED Holder - 10mm (Chrome Finish) - COM-11148 - SparkFun Electronics
LED Mixed Bag - 10mm - COM-13326 - SparkFun Electronics