IE7 Release Candidate 1 Standalone
You can pick up a standalone version of Internet Explorer 7 Release Candidate 1 (RC1) at Tredosoft.
I haven’t tested it out, as I do in fact have RC1 installed as my ‘official’ version of IE, and use a standalone version of IE6 for backwards compatibility testing. It looks good though, and appears to be a ‘proper’ standalone version which fully identifies itself as IE7, meaning conditional comments ought to work fine.
Why would I want a standalone anyway?
Since you can only have one version of Internet Explorer installed on a single Windows system, testing a website across multiple versions of IE very difficult. That’s where standalones are very useful, allowing you to run multiple versions of IE side by side on the same machine. For web developers this is a must.