Yup my hubby of 6 years (we've been together for 8) on yahoo.com! We didn't do the 'normal' online dating thing, since we were in the same city. Exchanged maybe one or two emails then we met for one date in a public place. My college roommate at the time was on alert, and the rest was history. He was the man I had been looking for the whole time in college.
I met one other guy on match.com, but turns out we were more of good friends than any romance. My roommate actually met her husband through him :) I haven't had any bad experiences, but things have also evolved so much since I was on a dating site.
As others have said be cautious, and follow all the safety rules, but I wouldn't necessarily exclude it from her repertoire of dating avenues :) Good Luck!