+1 for imgur, I use it all the time. There's an 'embed code for bulletin boards and forums' option that is exactly what you need to copy/paste here to get the image to appear.
You don't have to sign up, but if you do it makes it a lot easier to keep track of all your images, create albums for them etc.
And here's a pro tip which applies to any image links: if you don't want to resize your images (or forget to), you can also force them to appear on the forum at a sane size by editing the code as follows:
to
[img width=800]your URL here[/img]