Cornell University's vegetable varieties for gardeners
I found a great site for information of vegetable varieties. They have thousands of varieties listed and rated by members. The site is CORNELL UNIVERSITY'S VEGETABLE VARIETIES FOR GARDENERS.
The site is not a forum but a searchable database where members can post reviews for specific vegetable varieties and keep track of what they grow and review.
Here is a link that might be useful: CORNELL UNIVERSITY'S VEGETABLE VARIETIES FOR GARDENERS