What are some recession proof business on the web?

Offline there are tons of local businesses which are known to be recession proof (ex: laundromats). What are some web equivalent verticals that would qualify?

Almost every industry takes a hit if the global economy tanks, but here are some verticals that might be more recession proof than others:

• Pets -People aren't going to stop buying dog food to save money.
• Health care
• Education
• Tax prep and filing

People always say "death and taxes" are things that nothing impacts, including the economy. Bring something to market in those two industries and the economy won't matter if it dips.

I would add babies and children. Along with pets, people have to spend money on their babies and children.