I have a bunch of NS wallpaper I want to share with the NS community but I ran out of space on my ISP.

What are my options ?

I know imagehack but are there limits to sizes and amount of images before they start charging me for it ?

imageshack won't charge you, and will not resize unless you specify.

You can also use photobucket for smaller images under the largest imagesize cap, and keep your stuff together. (also free, or pay for other perks).