Internet Explorer 7 Beta 1
Apparently this site is offering a download of the IE7 Beta 1, which is supposedly for developers only, unless I missed some announcement that they have released it to the public. At anyrate, if you are wanting to try it out, here is your chance.
I will say that from what I have read, this is really only good for seeing the interface change and maybe playing around with the RSS/Web Feeds feature. The real bug fixes (like all the CSS releated bugs) are not going to be in place until Beta 2.