BCU Coach, Howard Jeffs recently rolled out a series of quick-repair kits developed specifically for kayakers. The nice thing about them is that they are individually packaged, sealed in plastic and ready to go when you...um...smash your boat and need to fix it, often right there on the water.
There are several different repair kits (both temporary and permanent) for both plastic and composite boats including an easy to apply patch using Denso tape or a full-on plastic welding kit to plug a hole.
Jeff also released a series of videos explaining the products and their use. Here are a couple of them:
More info: howardjeffs.com/essentials/accessories-equipment-2/