Ask HN: Tools of the trade, 2010 edition

When I first started delicious, we had to host most of the services ourselves. CVS, mail, mailing lists, etc etc etc.

These days, lots of that stuff is available as SaaS. What are the tools and services people use instead of hosting their own?

(I'm not talking about actual production services like EC2 and Heroku and whatnot. We can go over this in another thread.)