Check out these big 10mm common cathode through-hole LEDs! The opaque epoxy package causes these LEDs to have a soft, diffuse glow.
Gikfun 10mm LED Emitting Diodes Light Lamp Diffused F10 Round Led for Arduino (Pack of 20pcs) AE1258 : Industrial & Scientific
Diffused LED - Yellow 10mm - COM-10634 - SparkFun Electronics
Diffused Leds Australia
RGB LED Clear Lens Common Cathode (5mm) - COM-16911 - SparkFun Electronics
Diffused LED - Green 10mm - COM-10633 - SparkFun Electronics
NTE30159 NTE Electronics, Inc, Optoelectronics
COM-11120 SparkFun Electronics, Optoelectronics
LED - 10mm Cycling RGB (fast) - COM-11453 - SparkFun Electronics
COM-11148 SparkFun Electronics, Optoelectronics
LEDs and Illumination - SparkFun Electronics
Diffused LED - RGB 10mm - SparkFun Electronics - COM-11120
LED - RGB Addressable, PTH, 5mm Diffused (5 Pack) - COM-12986 - SparkFun Electronics
Adafruit 680 Diffused 5mm Fast Flashing RGB LED - 10 Pack
RGB Products - SparkFun Electronics