On the LogicPool site there's a new post with a list of PHP+MySQL code generators you can use if there's not a specific framework involved in your application (most of those come with code generation tools already).
Some of these tools can rapidly build a fully functional application, but there's more to most useful applications than simply displaying a list of fields for users to fill out and viewing the results from an admin only accessible area. Most applications will need tweaks that can be small to large depending on the requirements. Keep that in mind when looking at these products as the amount of effort required to tweak the code produced by these tools.
Tools on their list (some free, some paid services) include: