Hey All - I just thought I'd add that you can increase the germination rate of old seeds if you provide an ideal and controlled germination environment for a given seed. It can get pretty complicated and specific if you have some old and rare seeds you really want to pamper, but basically I'm just talking about getting ideal temperature, light/dark, and moisture/oxygen levels.
It's certainly not as impressive as germinating 30 yo seeds (wow!), but I tried this out recently in a crude sense by pre-sprouting some pepper seeds from my first year gardening (4 years ago) and was surprised to get 100% germination in only four days! They had been stored properly for the last couple years but before that there were just in a box in my basement. I folded over toilet paper squares twice to get a small square, dipped those in water and put the seeds on, folded them once more, ran my finger over them so they were very damp but not sopping wet, and put them in an open ziplock bag. There's a little pipe coming out of my water heater that's about 95F, so I put the bag inside a folded hand towel and managed to get a perfect 85F.
It doesn't work with everything - I had some equally old lettuce seeds and did the same ziplock method but sitting on my window sill (so only ~65-70F but with sunlight) and while buttercrunch germinated pretty well, Red Romaine and Brune d' Hiver had 0% germination.