There are some good discussions on this subject here:
- Add an interactive system to glean diagnostic features from identifiers and show them to observers (feature request)
- Expand the Similar Species tab into an editable identification guide (feature request)
- Photo annotations (feature request moved to general by staff)
- Adding useful ID info to taxon pages (general)
- Photo taking recommendations by taxon? (general)
- Observing & Identifying Wildlife - wiki (nature talk)