Mod request - Random IMG Block

[Graham Barns]

Hi I need a block that will do the following:

If I make a directory and upload all full size images into it, I need this block to automatically resize them down to a thumbnail size and when clicked the thumbnail will open up into the normal size version of the image. The thumbnail in the block has to be random.

I have seen some random image blocks but not one that does this.

thanks
Graham Barnes