Thanks for the comments. I just did it because I'd thought about it a couple of years ago and finally found some time to see if I could get it to work! So I guess I did it out of interest more than anything else. There are quite a lot of molecular visualisation apps around but very little to create objects directly in C4D. I also wanted it to be procedural so an ObjectData plugin rather than a script looked the best bet.
It only does the classic ball-and-stick appearance ATM but I might extend it if I revisit it at some point. Here's another render, this time using different materials per element and some lighting: