Postimg.org is free, and very friendly to posting photos on forums. One of the available options is to post a thumbnail to a forum, and have it expand with one click, then click again for a FULL size view.
I previously posted this same image (courtesy of Ray L) here using Photobucket, but here it is using the "forum" feature of Postimg.org:



Try clicking above, then click again after the larger image is displayed. This is all built into Postimg and very easy to do.

Oh, and its free, too!

I have switched to Postimg, but Photobucket images I made in previous threads are still at Photobucket. When I checked yesterday, they were still visible, but my account usage is very low and Photobucket may not have noticed that I use them as a 3rd party host. In any case, I was very tired of the slow loading at Photobucket due to the incredible volume of ads they were pushing. I won't be back.