SQL Server Integration Services (SSIS) does a good job of this I think. SSIS is made for manipulating data flows. The flow of data happens to be very well represented in many cases by visual network flow diagrams. Most of the common patterns of data flow are implemented as drag and drop widgets.
That said, as necessary, you can do pretty much anything in that environment as code if you want. The best thing about the language, though, is that /if/ you go down the path of coding something out instead of using a common pattern, it forces you to ask "Why am I doing something out of the norm here?" Sometimes you have a valid reason. Sometimes you don't and that question course corrects you back into a maintainable architecture. It's a very niche language (even mostly vendor locked down), but I think it's a great example of a visual programming environment that's mostly great to work in.
That said, as necessary, you can do pretty much anything in that environment as code if you want. The best thing about the language, though, is that /if/ you go down the path of coding something out instead of using a common pattern, it forces you to ask "Why am I doing something out of the norm here?" Sometimes you have a valid reason. Sometimes you don't and that question course corrects you back into a maintainable architecture. It's a very niche language (even mostly vendor locked down), but I think it's a great example of a visual programming environment that's mostly great to work in.