I have just updated the forum so that you guys can now display full rez images within your post, instead of thumbnails you would have to click on.
You just need to upload your file as an attachment (as usual) and then go to the small arrow next to the attachment button and pick your image.
It will include a line like : [ATTACH] attachment id
and your image shall display full rez in your post!
When editing an existing post, you will need to go into the "Go Advanced" editing mode (next to the save button) to see the paperclip symbol.
Let me know if you have any questions.