Free hosting usually isn't worth it in the end, but if you have to go that way make lots of backups of your site.
Here are some free providers that are nice to their members and have good features:
www.freewebs.com No forced advertising! Tons of space and bandwidth, can handle perl and php.
www.spaceports.com Banner on top of all pages. I think 30 megs space. 5GB bandwidth. Perl, php, and MySQL available for free after you request access.
www.fairmount.com No forced advertising! I think unlimited space and 2 GB bandwidth. Perl, php, Python, MySQL, phpmyadmin, CPanel. The catch is, it is not automated signup and they may reject your application.
http://www.1asphost.com 100 megs space, banner on top of page, unlimited bandwidth, can handle asp, comes with MSAccess database.
www.stormloader.com 50 megs, top banner, unknown bandwidth.
There are tons more, but most of them either don't have many features or else they treat their members horribly.