I've also been looking for something to keep photos from being accessed. I have found out that you can password protect applications (like your photo viewer) but I haven't found out how to password protect folders/data. For the time being, I have made the photos I want to protect "invisible" by putting them in a folder that's name begins with "." (ie ".private". Astro file manager has an option to view invisible files or not, so I'm leaving them unviewed (invisible) until I want to access them, then I switch to view it until I'm done.
I like this - BUT, the delay doesn't work. Is it working for you? I want it so that App Lock only kicks in if my phone hasn't been touched for 5 mins or so i.e. I left it somewhere or someone stole it and put it in their pocket or turned it off temporarily... does that feature work for anybody? Not for me :\
HideNSeek is great. it shows up in your app tray as a flashlight, when you open it it just gives you a white screen, you have to push menu 3 times then enter a password.
It will let you hide any file, picts, videos, ext.