Ok, while I cannot help my vegetarian friends until they help themselves, I thought maybe I could at least help out those who (for whatever reason) do not eat pork. (But really, none of these alternatives will taste as fabulous as the original pork product... at least not in my view. But, I shall try to enlighten a bit.)
The traditional "prosciutto crudo" is the more familiar form, being dried cured leg of pork, but there is also "prosciutto cotto" which is slightly cooked as well. While "prosciutto" is the Italian word for ham, (as opposed to "maiale" which is pig or pork) it does not have to be made from pork. It can be made from lamb, goat, duck, or beef as well. You just have to look a little harder.
The lamb is called "prosciutto d'agnello".
A beef option would be "bresaola". (I believe this is a dried, cured, top round type cut.)
And of course, the most readily available option would be turkey bacon, which you can find at just about any supermarket, but that is more of a bacon-swap than a cured-pork swap. They do have different qualities, but in a pinch, you could probably make it work. (You just won't find it in my house.)
Just keep in mind that, since this is a cured product, it intensifies the flavor, so make sure whatever you use comes from an animal you like to eat anyway. (I love duck, but I have had some duck prosciutto that was the nastiest thing... ugh.)
But in my humble opinion, nothing beats traditional pork prosciutto. It's light, delicate, salty, a little chewy... but if you put it in the oven to crisp you have a FANTASTIC crispy topping for pastas, salads, garnish, or just a snack for yourself! In my world, and in the words of Homer Simpson, the pig is a "wonderful, magical animal" that provides oh-so-many tasty options.
So some websites you could look into ordering other options from (maybe)...
This store sells lamb prosciutto: http://www.salumicuredmeats.com/ in Washington state.
More info on Italian cured meats here: http://www.italianmade.com/foods/cat18.cfm
This is my favorite UWS place to get freshly sliced anything (but mostly pork) product: http://www.salumeriarosi.com/
Good luck, you crazy, foolish folk.