Now that the Photobucket guys have turned all corporate and not allowing hotlinking to forums etc without a premium account, now would probably be a good time to revamp our hosting and posting pics thread.
There are many other services which are still free and require no signing up to do it. Amongst these are:

I find postimages is very quick and easy and allos you to resize images, give them an expiry etc. General rule of thumb is 800x600 is plenty for most pictures though feel free to go a little larger if it deserves it, landscape pics or sale item that needs a specifically sharp larger pic to cover detail.

Basic instructions: upload pic, copy the direct link of the image and post it to the forum using the [img] and [/img] tags before and after the link so becomes [lmg][/img] and when posted appears as the image.