None of which I am aware - I'd bet that you could get a .30 Luger barrel made up really easily. I suppose you could also go .41 AE with a custom barrel. Since this gun was primarily designed for the American market, I doubt you'll find a lot of Euro barrels designed for those countries that don't allow 9x19, but allow similar substitutes.
The problem preventing switching the 9mm bbl with one for the more-popular-in-this-pistol .40 S&W is that the case head of the 9mm is smaller than the .40. The 9x19 P239s sure shoot well - enjoy yours!
Howdy sir, and +1 with Mr. Erich. If you had a 239 in either 40 or 357Sig, you could change within those two calibers by swapping out to the other barrel and with the 239, changing to the other magazine. With either of the larger two calibers, you could also purchase a 9mm down or conversion barrel, and fire the 9mm in your 239 using a 9mm mag.
Unfortunately you can change down, but not up. The barrels that Sig sells by model numbers, ie, 239, 229, 226 and others, are designed to let you easily change between say a 40S&W and the 357Sig. But neither barrel will fit into your 239 9mm slide unit as the barrel opening in your 239 is not large enough to accept either of these other calibers. The 9mm down or conversion barrel is built to the same outer dimensions as the 40/357 barrels, so it would fit properly in the larger barrel opening in those slides.
Hope this helps, although it is probably not want you wanted to hear. Sorry.