Unfortunately, we've had to disable attachments. The original SMF implementation was crumbling under the weight of so many users and the data they were using -- and that was back in December!
Instead, if you want to embed a picture, use the IMG tags (first on lower left). Below is a tutorial from Lenny, founder and benevolent goddess of the art threads.
(BTW, +1 for Discworld reference...)
Inserting Images, Resizing, and Linking Back to the Original
Currently, attaching images to a post is impossible due to lack of space. Hence the creation of this image linking tutorial! Remember, only insert images from sites that are fine with hotlinking (for example, if it's an image you've personally uploaded to imgur, deviantART, tumblr, photobucket, etc. - that should be fine).
Inserting images is pretty simple! Either click on the Insert Image button (a little picture of the Mona Lisa, located below the Bold button), or insert the code manually:
[img][/img]
Your actual image will need to be hosted on another site (dA, tumblr, photobucket, flickr, there are a myriad of them out there). Once you've done that, right click on the image and select "Copy image location" or something with similar wording (might differ between browsers). Then paste the resulting URL between the code, like this:
[img]http://www.example.net/example_pic.png[/img]
And that's it!
Now, if you want to resize your image because it's too large, use the following code (with the number used being the pixel size you want):
[img width=300]http://www.example.net/example_pic.png[/img]
Or this:
[img height=300]http://www.example.net/example_pic.png[/img]
Or even this (only recommended if you know the exact ratio of your picture, otherwise the image gets distorted):
[img width=300 height=300]http://www.example.net/example_pic.png[/img]
Now, if you want to link back to the original picture, just wrap the whole thing in a url, like this:
[url=http://www.example.net/examples][img]http://www.example.net/example_pic.png[/img][/url]
And that's all! Pretty simple, though it might take a little while to memorize it. If anyone has any questions, or you feel I've left something out, just ask and I'll answer questions and edit this<3