Sometimes people do screwy things to extensions because of limitations set up by hosting sites. Usually they'll say something in the notes about changing it. Also some .exe's are self extracting zips. To be on the safe side, you should check with a zip extractor program. And on the topic of Macs, .sit is another file format popular with them.

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
Also feel free to browse my freebies at ShareCG.
There might be something worth downloading.