I heard about those eye lash lengthening products. what are your thoughts on them?

They are safe, but..: They should be confined to the lashes, since they may permanently affect eye color, turning blue eyes to brown. They will lower the eye pressure as well and cause the eyes to appear red and inflamed if they get onto the white part of the eye, the conjunctiva.

Which ones?: There are false lashes, lash extensions, mascara, medications such as lattise that make lashes grow longer. If you are interested in latisse, (bimatoprost) you should be informed about the rare potential side effects (see some listed in the other response).