Well, these are reconstructions. I won't use real girls' images on the site ;)
However, there's a very easy way to get a girl's picture in your phone. And if you take a bunch of numbers or are the busy/distracted sort, it's very helpful.
The way you do it is after she's agreed to the date, and you've taken her contact info, you then say, "Hey, send me a pic real quick so I have you in my phone." Some girls will send to you then, some will send after. Some won't send, which is a little negative compliance but not the end of the world.
In general though, she's complied with the date request, and complied with the contact info, and it's usually not much work to get her to comply with the picture request after these two.
Pictures can be a lifesaver if you bounce around a bit and take numbers fairly often. Girls may fall off your radar and resurface later, and if you don't have a picture you will sometimes have no recollection of whom this girl is. With the picture, one look and usually you'll say "Oh yeah, I remember her!"
Very helpful to have.