Does anyone know if smoking might cause menstrual cramps to be more severe?

Obviously smoking is unhealthy, etc. etc. But to answer your question, while smoking actually lowers estrogen levels, studies have shown that women who smoke are twice as likely to experience dysmenorrhea as nonsmokers, and smoking prolongs the symptoms of this condition [Harvard School of Public Health 108:1019-1022, Chen et al]. Hope that helps.

It does with me
Let's put it this way, the better your overall health and the closer you are to your ideal weight, according to a body mass index calculator, the less severe your menstrual cramps are likely to be. So, that being said, stay healthy (don't smoke), keep your weight down, exercise, and eat a low fat diet. More here:
http://www.drmcdougall.com
I smoke when it's my time of the month and I feel no different.
Smoking calms the body in most people.

If your cramps are really bad get an electric heating pad. If you're low on funds get an old tube sock and put about half the sock full of regular white rice it it. Tie the open end of the sock as tight as you can as far the the open end of the sock as you can get to allow movement of the rice (you want it sort of feeling like a water balloon). Toss this bugger in the microwave and nuke it for about 1 minute... walla! perfect heating pad. Place your electric heating pad or rice-sock right above your pelvic bone. It will help you out a lot.
I'm a smoker and I'm female.
i dont think so
Smoking is really bad for you, it affects you systemically, and you may have many symptoms that would improve if you quit. Many smokers have reached the point where they can't feel the pain in their bodies. Doesn't mean nothings wrong, means they don't feel it (perhaps ever, perhaps anymore). So some people might say yes, some no, but the important thing is what's best for you.

Even if smoking completely alleviated menstrual cramps, I wouldn't put up with the risk to my health.

If you won't stop smoking, at least make sure you drink enough water, preferably warm or room temp (less jarring than cold). During period especially, but every other time too. It will flush some of the carcinogens out.