Features I've been thinking about:
- More Domain Extensions
Automatically adding your TLD extension based on your region
Show multiple Domain Registrars for each TLD
Show most viewed available domain names
Add Regular Expression searches to available domain names
Improve the TLD extension selector (maybe it could automatically reload the page when you select extra TLDs)
Add watch feature to check if domains get renewed (maybe an email report)
Improve deleting domain list
Improve domain wizard
Regular expression search against registered domains
Any others?