I have grown heritage tomatoes and zucchini, both of which did very well, though the tomatoes were incredibly slow to ripen. Heritage seeds are a bit limited in Australia due to our very strict quarantine laws, but there's still quite a few available, especially for tomatoes.

The problem with the heritage zucchini plants was that we ended up with six of them, and they went absolutely wild. We were supplying the entire town's zucchini needs at one point.