How can I wirelessly transfer photos from my iPhone to my computer without using Photostream?
You could use an iPhone app like WiFi Photo Transfer (There are a few of those available in the app store), but I don't think this is going to be any more convenient than simply plugging your phone in.

Another way would be to take the photos with Dropbox. The Dropbox iPhone app let's you take phones, which would just appear in your Dropbox folder on your Mac.