The Bleeding Snort community is always soliciting new signatures and ideas. Regardless of the maturity or sanity of an idea or signature, please submit them.
You can submit signatures directly to the Bleeding Snort Team at firstname.lastname@example.org. (Please avoid sending directly to an individual admin. If they happen to be offline or out your sig may be delayed.)
The forums on this site are a medium to bring up and discuss new ideas.
We also monitor the Snort-Sigs list maintained at www.snort.org, as well as a number of other mediums.