I really like the large palm plants that were popular during the Victorian era, foremost of which would be the Kentia palm. The seeds of this plant are like mini coconuts and are notoriously difficult to germinate, even for a palm. So having spent a sizeable sum on a batch of 20-odd seeds, I went to the googles with pleas for help, and Science answered the call. To wit:

Breaking Dormancy In Kentia Palm Seeds [PDF]

I'm currently recreating this experiment with my seeds, which found that a brief soak in a solvent of gibberellic acid and dichloromethane, followed by water soaking and then planting, resulted in an 90% germination rate. For comparison, seeds soaked in GA3 and water had a 40% germination rate, and seeds soaked only in water didn't germinate at all!

Since the GA3 in the solvent will be good for a few weeks, I may try soaking other troublesome seeds in it and see what happens. Syrian Rue springs to mind as a good candidate, assuming what I'm taking for a bag of seeds isn't in truth a bag of gravel.