Microsoft software for Windows 1.0
Microsoft chose not to port its most popular applications to Windows 1.0. Word for Windows was released in 1989 and Excel in 1987 (both ran exclusively on Windows 2.0 or later). Multiplan and Chart were never ported to Windows, and neither were various development tools and languages (aside from those that were part of the official Windows 1.0 SDK). Microsoft Mouse was meant for DOS only anyway, as Windows had its own driver model.
I believe the reason for this is Microsoft's rather delicate relationship with Apple. Word and Excel were developed for the Macintosh, which initially badly needed applications to succeed. In order to develop these applications, Microsoft had some internal insight into the Macintosh and its software. Releasing Windows ports of their apps could jeopardize their contract with Apple, especially considering all the similarities between Windows and Mac OS (which later resulted in a lawsuit by Apple anyway).
However, since Windows 1.0 had decent support for DOS applications, this wasn't of critical importance. Users could still run DOS programs under Windows 1.0, they just couldn't use all the fancy GUI features provided by Windows. Still, this decision probably had an impact on Windows 1.0 sales.
One notable exception was Microsoft's demonstration program for their first CD-ROM conference in 1986. It was a multimedia encyclopedia with text, photos, sounds and animations. However, the product was not announced for general release, though attendees recieved the demo disc, apparently. A year later, the first version of Microsoft Bookshelf, for DOS rather than Windows, was announced at the same conference.