I worked on one, for a large telecom: It was simple business software, which before was written either in Cobol or plain old C. The large performance penalty that Java had back then was far less important than having to mind memory leaks in C, and people already thought Cobol was a language without a big future. It was also at the time before the dominance of x86 on intel hardware, so the compile once, run anywhere idea was also quite attractive to people that knew they wanted to change hardware vendors.

It took a few more versions, and a few more JVM performance improvements, before Java was a competitive for a broader spectrum of uses, but it was competitive for business very quickly.

Java 1.0 got people excited about applets, but Java 1.1 really got people going with server side. Microsoft joined in with Visual J++ and it was also obvious that it was going to be important on the Mac. (I couldn't get it to do anything useful on my IIcx, unfortunately.) Then, with the introduction of the HotSpot VM along with Java 1.2, it got really good.

These days, we're spoiled with our wide variety of available, free languages, but at the time most software for Windows was written in Visual Basic, Pascal (Delphi), or C++, none of which was free. And Windows was almost all of the desktop PC market share. The promise of write-once-run-anywhere also made Java really interesting.