Blockchain explorers will come and go, but I think it may be worth having a canonical question with a community wiki answer which lists those that are live. We can encourage people to edit the answer if they spot a site that is down for a few days. What do you think?
Great idea, I have started a community wiki for this purpose as the answer to What Ethereum blockchain explorers exist?
Yes I think so, and answers that mention explorers can point to the wiki instead of a single explorer.