Photobucket's size for message boards (640X480) fits the forum layout nicely and displays on 800x600 screens without scrolling being necessary. However although it works well for landscape orientation it is not so good for portrait orientation because the height is limited to 480 pixels so the width then becomes reduced to about 360 pixels, depending on the original picture proportions, making a rather small picture. So it is just the width taht needs limiting really.

I rather favour the use of clickable thumbnails. They take up minimal space on the page but can link to large pictures which open in a new window under control of the browser magnifier. It is also up to the reader whether he views the large pictures or not depending on his interest in them.

If you like cats you can click and view the full screen picture of the "black shadow" from next door. If you dont then you dont bother.