In WinMo day's I used it often. Since I got my Droid X(I know, I'm posting in the wrong forum but I didn't see this on Android Thoughts) it's very rare.
I used to love having an sd slot so I could take pictures with my point and shoot, take the card out, and review them on my 4" screen Pocket PC. Even with a microSD card slot I had an sd adapter that I would put it in so I could use it in my camera. It was also handy to transfer files to PC's. People often had card reader's around even if they didn't have a mini-usb cable.
With my Droid X I think two major things have changed. It has DLNA which I use to put photo's on my PS3 now. It has an awesome camera! At least for outdoor shots it's excellent! Video too! I can even get good indoor shots sometimes. I use my point and shoot much less and, since I have a good Facebook app, I can easily upload pictures directly to facebook without using my PC or PS3. It was just clunky, at least for me, in WinMo.