As you probably have noticed, I host my photos on my own web site, under my gallery. I use the Gallery software and it works pretty well.
In the past I submitted to Railpictures.net but I stopped a few years ago. Their screeners were getting too picky for my tastes and it was not worth my time to resubmit over and over with minute changes in the pictures. Not my thing. I visited them a few days ago and I see their ads are getting more and more spammy. I had a popup that had no choice but to click OK... so I used Task Manager to kill the browser. I asked Railpictures to delete my account and my photos, and they have done so.
There's another photo sharing site, Railpictures.ca, that does not seem to be affiliated with the .net version. I may have posted about that before. I heard that an Arizona Eastern E8 (AZER 6070) is in Canada and in fact there are two pictures of it on Railpictures.ca. I'd embed a small photo linking to their site, but their terms do not allow that.
Of course there is Flickr, now owned by Yahoo!. It does a decent job and I would recommend it to most people who want to throw some photos on the web.
RRPictureArchives is another good one. I like how well organized for searching it is.
What do you use for your photos?