I have used them in the past and they can help in some areas but be very careful of the information that you put on the site. Even if it is secure and a reputable company, spyware can be on your computer allowing someone else to see what you are putting in the blanks. :)
Okay another website I just read about today- it was too funny but not the worst of ideas. It's called www.mizpee.com. It helps you locate clean public restrooms. I was very amused by this but after my last experience, wouldn't necessarily shun it yet. You can download it to your cellphone so you can find one in your nearest location. Good luck.