before you have eaten up your favorite tomatoes, think about making some seeds out of them to grow them again next summer. it is very easy and all you need are some tomatoes, jars and kitchen towel or coffee filter paper.
half the tomatoes and scratch out all the seeds. place each sort of tomato in a separate jar and cover with water. the idea is to copy the fermentation process of a birds stomach to mortify all the germs. wait a few days.
decant the seeds after a few days through a sieve and let them dry on a kitchen towel or coffee filter paper. once they are dry, just fill them in small paper bags, label with the name of the tomato sort and store in a dry and dark place until next spring when you can start to grow new plants from your own tomatoes.
i read about this process in the book of prinzessinnengarten, an amazing community garden project. personally, i have no experience with it and hope that it will work. i will post my experiences with it next spring and summer. and i am happy about your feedback if you try it out too.