Images to play with could include wind or a wind pane (North, south, east west). Zephyr means "west wind" and was chosen both because Stanford's motto is "The Wind of Freedom Blows". It is a favorable wind, and in many languages, is similar to the word for soul, spirit, essence of the human being.
If the pictorial mark could be a bit abstract (better that than cartoonish).
Regarding the 3 example logos we like from the 99design gallery, the Brickell group is nice in its use of the just the letter in the diamond--simple and elegant, although that logo seems pretty generic--it could be the logo for just about any real estate firm. The other two are nice in that each has a single image that could almost be used by itself to signify the company.
The following comments correspond to the attached pictures I uploaded:
1: We like the idea of have the "Z" be stylized and act as a logo. This one also evokes wind kind of nicely. The Logo could also be "ZI" (Zephyr Institute)
2-4: These are images of the god Zephyr. There is something about the abstract dynamism of this that we like. 2 also evokes a creative force, which is central to the spirit of Silicon Valley.
5: The font here is nice, and the logo incorporates the purpose of the organization (a lavendar farm)--obviously a very different purpose than ours, but we like how they evoke their identity.
6. This simple symbol is ok, but a bit too abstract--almost looks like an electrical outlet
8-10. These would be too corporate / tech startup-y for us. We are more of an academic organization.
11. We don't like the face or the font--too swirly.
12. The font here is OK. The face blowing wind is too obvious, but the "Zephyr Eco" icon is a little too abstract. Visually, they are OK though.
13. This is an institute similar to ours, located in Berkeley. We like that they used a local trend--an arts & crafts stained glass window--to tap into the local flair. This particular style wouldn't work for the Stanford community though, because that trend isn't prominent here.