I just went looking for one the other day... This is the one I found. The 2 games I tried seemed to work, but I was unable to make the controller affect the games...

This release was a few months ago, so it's relatively current.
Project Tempest v0.5 (03 March 2003)
---------------------------------------
What is Project Tempest ?
-------------------------
Project Tempest is worlds first working Atari Jaguar emulator. It currently runs several
commercial games.
System Requirements
--------------------
Pentium III/Athlon 800+ MHz
128MB RAM
DirectX 8.0 or higher
Windows 9x/ME/2000/XP
A faster processor is seriously recommended !
For sound emulation, you probably need a 2+ GHz processor.