thank you for the suggestion, you can post it in our Votebox:
Also, please clarify what features would you like to see in this calendar? Should it rather be an advanced query system or do you think about something like an alternative calendar-like view for adding tasks?
For now, you can export your Todoist tasks to many calendars, incl. Google Calendar, iCal, Outlook etc. using our iCal feed in Preferences -> General.