And from the U of Maryland: http://umm.edu/health/medical/altmed/supplement/carnitine-lcarnitine

[h=2]Male Infertility[/b]Low sperm counts have been linked to low  carnitine levels in men. Several studies suggest that L-carnitine  supplements may increase sperm count and motility.

[h=2]Erectile Dysfunction[/b]Preliminary  studies suggest propionyl-L-carnitine may help improve male sexual  function. One study found that carnitine improved the effectiveness of  sidenafil (Viagra) in men with diabetes who had not previously responded  to Viagra. In another study, a combination of propionyl-L-carnitine and  acetyl-L-carnitine improved the effectiveness of Viagra in men who had  erectile dysfunction after prostate surgery. More studies are needed.

[h=2]Peyronie Disease[/b]Peyronie  disease is characterized by a curvature of the penis that leads to pain  during an erection. One promising study compared acetyl-L-carnitine to  the medication tamoxifen in 48 men with this condition.  Acetyl-L-carnitine worked better than tamoxifen at reducing pain during  sex and reducing the curve of the penis. Acetyl-L-carnitine also had  fewer side effects than tamoxifen. More research is needed.