If you were using MobileMe to host your website you can continue to use iWeb but, will need a 3rd party web host to upload your websites to. Depending on the version of iWeb you are using you have a couple of publishing options:
iWeb '09 (3.0.4) you can publish to an FTP Server or a local folder. ( With the built in FTP in iWeb you will end up with an address like "www.YourDomain.com/sitename/Home.html )
iWeb '08 you can publish your website to a local folder
Publish to a local folder is located in the file menu I do believe.
I have been using IX Webhosting for several years with little to no problems "usually the problem was something I did" and they have been quick to solve any issue I have come across. The have plans that start at $3.95 a mo (USD) and their customer service is top notch.
http://jeffnitschke.com/IXWebHosting.html
http://jeffnitschke.com/wordpress/2012/06/how-do-i-move-my-mobileme-site-ix-web- hosting-blog/
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