Flat Text Database Scripts

[MyDigitalpoint]

Believe or not, there are still many hosting providers that does not allow their customers to run a MySQL database, whether cheap hosting or free hosting services, so people need to look at a simpler solution to cope with this limitation.

Some other people may prefer a flat database because is easier to connect and maintain, but whatever is the reason someone is using this type of text databases, it would be interesting to hear some opinions, not about how fast or convenient is MySQL in comparison, but what kind of flat database is better and more efficient.

Flat text writes on text files, as easy as that.
XML database does the same but over an XML-formatted DB
SQlite is a flat database engine that offers better security and performance

I think I'm missing some other options so I would really like to hear your input about these or any other non-MySQL databases that can be used as an alternative.