Yes, but some may not produce the same plants as their parents. Seeds from hybrid cultivars would likely be inferior to what you grew this year. If you want to grow hybrid cultivars, you really should buy new seed each year. F2-generation hybrids are almost always considerably different than the F1 generation.

On the other hand, open pollinated and heirloom cultivars are more likely to produce good quality offspring. Of course if you have two or more types of non-hybrid tomatoes, for example, and grow them in relatively close proximity, at least some of their seeds are likely to be crosses between the different types. If you only grow a single heirloom cultivar, the offspring should be the same as what you planted this year (unless a neighbor has a garden close to yours).