My husband's maternal lineage is almost entirely French-Canadian. This makes research both simple (I can focus entirely on one province; sometimes a second as families move) and difficult (there are ancestors with 4 or 5 names, not to mention the "dit" names).
This is probably my weak research point, so I am pleased that Cyprien Tanguay's Dictionnaire Genealogique is available online.
While there are errors, and it is best to verify events with church records, these 7 volumes are a wonderful way to get started on checking names and dates. This website is particularly useful to me, as I currently reside in Asia (off to Europe next year, we hope), and cannot simply hop in my car for a trip to Quebec.
I highly recommend this site to anybody with French-Canadian ancestors, with the reminder that - at some point - you should try to verify the dates and places with church records. Or at least include the caveat in your genealogy that Tanguay's books do have errors, so that perhaps future generations who have the opportunity to visit Quebec will take the initiative to do so.