The Utah Preppers Network did a good post on the jar sealing attachment that you can purchase for vacuum sealers. It allows you to vacuum seal jars of food to increase shelf life. It isn't an alternative to pressure canning but will work with things you would need access to regularly. Most people know that you can use vacuum sealers to seal food and prolong it's shelf life. They work great to preserve foods you have dehydrated, food that you want to freeze, or pretty much anything you want to seal.
You can also use the sealer to vacuum seal lots of non-food items. I've seen people vacuum seal pairs of jeans, shirts, and socks to compress their size to put in one's Bug Out Bag. Knine, one of the KPN contributors, posted a tip and said he vacuum seals rolls of toilet paper which makes them a lot smaller and easier to store. The possibilities are endless when using your vacuum sealer. Obviously they use electricity so unless you have a solar setup you won't be able to use them off grid but they're very handy and will benefit you while you are