The advantages of refrigerator jam are numerous. First and foremost, you are making your jam as you need it and in smaller batches, which is a much simpler, less time consuming process. The second major advantage is that you can skip the canning process altogether, which for many people is a make or break point. Finally, you can enjoy a wider variety of jam this way, sampling all the amazing fruits as they come into season, without flooding your cupboards with jars of jam.
So instead of leaving the market with a flat of peaches to spend an entire afternoon in a hot kitchen, pick up 3 or 4 really juicy ones and spend less than an hour cooking them down with some sugar and maybe a splash of lemon juice. Ladle into a clean jar, cover and keep in the refrigerator. I usually finish my jam before spoilage is an issue, but jam lasts a good while when refrigerated, at least a couple of weeks. Cooking By Feel: Strawberry Refrigerator Jam will give you a more detailed explanation on how to make smaller batches of jam.
If you do want to actually can your small batch creations, Marisa McClellan did a great series on Small Batch Canning for us in June called Urban Preserving. You can also use her recipes but skip the canning process for refrigerator versions. Marisa discusses this in many of her post or in the comments section.
And of course refrigerator jam can also be frozen, although the same isn't true for other preserves like pickles. For more on freezer jams, visit Preserve Summer All Year Long: Freezer Jam and if you're in the mood for something piquant try Aunt Lorraine's Refrigerator Pickles.
(Image: Dana Velden)