VisualAge for Smalltalk was pretty impressive. A little nugget of history: IBM's VisualAge for Java was based on VisualAge for Smalltalk — which was acquired along with OTI — and ran a Smalltalk VM that ran both Smalltalk code and Java bytecodes. It carried over the whole paradigm from VAS, you had the code browsers, etc, as well as the very powerful GUI builder that VAS had. A pity the product never caught on.

They rebuild the product in Java, which later morphed into Eclipse, which despite all its plugins never provided the productivity boost that VAS (or even VAJ) provided.