I'm assuming you mean Wubi. There are three installers of that sort. Debian, which Ubuntu is very similar to, has a web-based installer at:
http://www.goodye-microsoft.com
OpenSuse has something called InstLinux which used to be an independent project anything could be installed with, and still requires enough prior assembly so I can't be bothered with it.
Many distributions, such as Knoppix,Damn Small Linux, Hikarunix or dyne:bolic are available primarily as live CDs. That is installing them is not the point. You can run them anywhere. Knoppix, Damn Small Linux and Hikarunix, like Ubuntu are Debian derivatives, in fact Knoppix, if you install it, will install as a vanilla debian system -- which means that at first the interface is similar to Ubuntu's but while the information is accessible it requires a deeper understanding of computers to run successfully. Dyne:bolic has something it calls docking which quite frankly, I've never gotten to work. If you want to try it go ahead.
In addition, Ubuntu, Mandriva, OpenSuse and other large distros have live CDs which enable you to try before you buy. Ubuntu calls its the graphical installer, and frankly I haven't found it to work as well as the installed version since 2005. Mandriva's works beautifully, but the only version of Suse I've ever had success with was one which a German University had on the net for two years which you could run from your web browser.
Gentoo and Slackware are two versions of Linux where this sort of thing is irrelevant, almost. I have been discussing my gentoo install with another user and I've lost count of the times when he's smiled and said, "They broke it again." If you want to use it you are making a commitment to debug it. It doesn't "just work". Slackware is more stable, but is the closest thing to a bare-bones vanilla installation of Linux short of Linux from Scratch, which you install by compiling it from the source code which you get from the various official repositories for each package, following the instructions in the Linux from Scratch how to manual. Dyne:bolic, which is an excellent graphics-oriented linux, seems to be associated with that movement.
Fedora Core has had excellent Live CDs for a while now, and the XO operating system, which OLPC uses, is built on Red Hat (Fedora Core, in other words). It's worth trying out that live CD because it uses Sugar, an implementation of streams for a user interface. This was what Gates called unrealistic etc, but it quite possibly IS the future of computing. Linux in general, not just Ubuntu had Compiz/Fusion/Beryl, a three dimensional desktop out and being discussed before Microsoft THOUGHT of Aero. You can buy live and install cds from many sources, or you can download the iso files and burn them yourself. You can also download them, burn them, and give them away or sell them.