You can either display a banner at the top of your page, or have an annoying pop-up window. Both options include an embedded watermark at the bottom right or their pages, which is cool to see, but gets annoying, and can sometimes mess up the page. Some people have reported it hard to access their account at times. A new, and major free web space provider, Fortune City has grown tremendously, and offers a free 20 megs of space. You are required to place a banner on your page.
Fortune City uses a city theme, which is different, and kind of cool.
Fortune City also recently added sub directory support, which makes organizing your files a lot easier. No single file can be larger than 1 megabyte. Some members have reported a lot of 'downtime' and times when it was hard to access their account. A good web hosting provider, IceStorm has fast connections and good service. However, they only give 3 megs of space, which isn't all that much.