I've seen people around here selling homemade crab apple jam. Here's a recipe I found online:http://www.canadianliving.com/food/crab_apple_jelly.php
6 6lb lb(2.7 kg) (2.7 kg) crab apples
4-1/2 4-1/2cups cups(1.125 L) (1.125 L) granulated sugar
Remove both stem and blossom ends from crab apples. Do not peel or core. In large Dutch oven, bring crab apples and 6 cups (1.5 L) water to boil. Reduce heat, cover and simmer, stirring occasionally, for about 10 minutes or until softened. Using potato masher, crush crab apples; cook for 5 minutes longer.
Wet and wring out jelly bag; suspend on frame over large measuring cup or bowl. Fill with crab apples; let drip, without squeezing bag, for about 2 hours or until juice measures 6-1/2 cups (1.625 L), adding up to 1-1/2 cups (375 mL) water if necessary.
In large clean Dutch oven, bring juice with sugar to full rolling boil over medium-high heat, stirring constantly; boil for 15 to 18 minutes or until gel stage. (See Gel Stage Test, below) Remove from heat; skim off foam.
Using funnel, fill hot 1-cup (250 mL) canning jars, leaving 1/4-inch (5 mm) headspace. Cover with prepared lids. Screw on bands until resistance is met; increase to fingertip tight. Boil in boiling water canner for 10 minutes. (See Canning Basics)
* Gel Stage Test:
• Remove jelly from heat while doing test.
• Chill two or three small plates in freezer.
• Place 1 tsp (5 mL) hot jelly or jam on plate and freeze for 1 minute.
• Remove from freezer. Surface should wrinkle when edge is pushed with finger.
• If surface doesn't wrinkle, continue cooking and repeat test every few minutes.