For long term storage, carve it in stone. That's monochrome, but it lasts longer than anything else. After that, oil paint seems to last quite a long time, then watercolors and charcoal (also monochrome).
For computer images, good quality, brand name CDs and DVDs are your best bet, but they won't last for ever, so it's important to have multiple copies of those (on different brands of media) and make copies of them periodically.
Also, you shouldn't just store the RAW files either. Five or ten years from now, you may not be able to find a program that can read the RAW files you use today. You can store the RAW files, but save the corresponding JPEGs along with them, just in case.