Ask Dan & Jennifer

Deviantart allows sexual pictures.. If you put the mature warning.. I think.. but it's not private. Then photobucket deletes those kind of pictures.
Soo.. I'm not sure..
Good luck finding one though.

MEGAUPLOAD - The leading online storage and file delivery service

It's been a while since I've used this so they may have changed the way it works since then. It's not an album so you can only upload one file at a time. I believe the file stays there until you decide to remove it. The url is given to you after the upload is done so you can give out the link as you please.

The best idea that I can think of is archiving the files you want to send in a .zip or .rar format. It doesn't matter which. You can then add a password that only both of you should know to it, and it wouldn't get out easily if you don't post the links anywhere online, and you send those to each other through IM or something. Learn more about archiving files with password protection by using Google.

Then upload them to "www.mediafire.com". You'll get a link to the download to share with whom you wish to download them.

Similar, but more security. Remember, there absolutely is NEVER security online, or in life. It's an illusion that's been around for a very long time.

"There is no security on this earth. Only opportunity."
- Douglas MacArthur