I would like to have a SQL database online, but don't want to deal with its care and feeding. There are some commercial offerings out there for hosted DBs, for example Amazon SimpleDB. Can anybody suggest others, and if they used any of these services what their impressions were? Anything that helps me make an informed decision would be appreciated.
Edit: Since there's no one true answer, I've made this a community wiki.
Google's AppEngine also has a SQL Database: http://code.google.com/appengine that is free, but it doesn't scale very well.
Amazon's SimpleDB is lacking a large chunk of the MySQL API, so if you want to go this route try and stick to SQL92 as much as possible. Also, keep in mind that you are changed per query. This means you want to make every query count. One way of doing that is by using relative updates:
UPDATE persondata SET age=age+1;
To be honest SimpleDB is a waste of money unless you need a large SQL cluster. I'd start off with a local sql db, when your load starts to get out of hand, move the sql db to its own server. After that, you will be looking at clustering your SQL db, and then SimpleDB starts to become an attractive solution.
Did you take a look the Amazon Relational Database Service. It is a MySql instance, and it is priced in a similar fashion to the EC2 products.