I know its largely irrelevant given the games relatively small size, DRM-free nature etc, but would you consider offering (if possible) steam keys for people who purchase it directly from you? I, for one, tend to bounce between my desktop and laptop and having Steam as a central repository for downloading and redownloading is always incredibly helpful.
It's trivial, but also a nice gesture to have the game properly integrated into Steam - a lot of indies (such as Defence Grid) have been selling Steam-compatible releases thru third parties... (just enter key etc.)
Of course, i'm giving my money directly too you because of the quality of all your output - Gabe & co don't need their cut.
