Win32 Bindings

There are two low level bindings and four thick level available:

1. Win32Ada from Intermetrics (comes with GNAT)
2. Win32 from Aonix

1 is freely available. 2 comes with the Aonix OpenPack and is 
not freeware.

1 is complete for the Win32 API as of Win NT 3.51 and is strongly 
types
2 Don't know, don't own it, but I believe is less typed then 1

There is also a partial thing binding to Win32 that covers some of the
newer NT 4.0 APIs in the user contrib section on the GNATCOM page

Thick level:

1. CLAW
2. Windex
3. GWindows
4. Jewl

2, 3 and 4 are freeware, 1 is not (but a light GMGPL version is now available)
and is available from RR Software CLAW is stable and has professional support. GWindows covers most of the Win32 GUI and includes ActiveX control support and
multiple event models (OO and Listener Style). Free support is available via the
GNAVI list (see http://www.gnavi.org) Windex
includes a nice section of the Win32 APIs. Jewl is a very nice binding designed for novices and students and is under the GPL (which means software written
with it will also fall under the GPL).