I have just uploaded v 0.1 of a Jmol gallery plugin for Elgg. It is similar to the Media gallery plugin but uses the Open Source Jmol Java applet for the interactive 3D display of chemical structures.
The current version simply displays chemical structure files (e.g. .cif, .cml, .mol. .pdb, .xyz) uploaded to a 'Your Files' folder. See this folder as an example. You will need a Java Runtime Environment installed on your local client host for the applet to work.
Hope it will be useful to Elgg-enabled chemists, biochemists, molecular biologists, crystallographers, science teachers, students etc.

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Close on the tail of Jmol gallery plugin v 0.1, here is Jmol gallery plugin v 0.2.
This version has the addition of instructions to enable the Jmol rendering of chemical structure files in blogs. You can see it in action here.
Amongst many other possibilities, it should make the generation of Molecule-of-the-Month-type blogs straightforward in Elgg.
I'm at the ElggJam07 at Brighton University later today, so if anyone wants to discuss this face-to-face fee freel to pounce.