Check out these big 10mm common cathode through-hole LEDs! The opaque epoxy package causes these LEDs to have a soft, diffuse glow.
RGB LED Matrix Panel - 32x32 - COM-14646 - SparkFun Electronics
LEDs and Illumination - SparkFun Electronics
Gikfun LEDs Diffused RGB Common Anode 4 Pins 10mm Super Bright Bulb La
LED HOLDER FOR 10MM LEDS
COM-11841
Diffused LED - Blue 10mm - COM-10635 - SparkFun Electronics
Diffused LED - RGB 10mm - COM-11120 - SparkFun Electronics
COM-11120 SparkFun Electronics, Optoelectronics
WP813GD Kingbright, Optoelectronics
Diffused LED - RGB 10mm, Sparkfun COM-11120
Diffused LED - RGB 10mm from MindKits New Zealand
LED Holder - 10mm (Chrome Finish) - COM-11148 - SparkFun Electronics
COM-11449 SparkFun Electronics, Optoelectronics
LED - RGB Addressable, PTH, 5mm Diffused (5 Pack) - COM-12986 - SparkFun Electronics
SparkFun Electronics COM-11451 Red, Green, Blue (RGB) LED Indication - Discrete 4.5V Radial
Diffused LED - Blue 10mm - COM-11161 - SparkFun Electronics