Rehost Image is a Firefox add-on that makes it easy to post pictures not yet on the internet. Just download the photo you want to post from your camera to your desktop. Resize, edit, crop, etc. Then drag it into Firefox and right-click. If Rehost Image is installed, the right-click menu will include an option to upload the image to a free image storage service and copy the URL to the clipboard. Once the URL is on the clipboard, you just post <img src="[paste URL here]">.
By default Rehost Image uploads to ImageShack, but you can configure it to use a different service if you want.
How did you type the tags and the phrase for posting a picture here without adding extra spaces to keep it showing?