A blog post on the Technipages website explains a way to do this. It involves downloading a program called iBackupBot, altering a file in your iOS device's backup, then restoring it. It's a bit of work, but if you really want to view full web pages with an iOS device, you might want to try it out.
[kirkmc adds: I haven't tested this, and I don't do enough web browsing on my iOS devices to need this. It's true that some sites minimize their content when you access them from a mobile device, but in most cases, this isn't a problem for me.]

