I feel compelled to type that my dad has one on his HP Laptop, and with his disabilities it's way easier for him to use that than to have to type his passwords all the time.
There is something useful about it.
I have about 10 PW's for my website - i'd actually love to just swipe my finger on something rather than typing and finding where i wrote them all down.
Would you now? Really there isn't software that does that. My laptop came with this fingerprint software that was like that except it only worked for IE, meh, and would put passwords in the wrong fields and submit the form. You also couldn't just swipe, you had to hit something like Ctrl Alt H and then click which website you were on then swipe. Not worth it.
Say no to swiping. Say yes to typing. (TM)