What are some alternatives to a database?

I want to store data and read/modify it on my Web server using Perl. I don't need something big and scary like SQL. Are there any modules or even just standard syntax for plaintext files to do this?

SQL is a good choice is disaster recovery and latency don't matter to you
Riak is a good choice if latency doesn't matter to you
If you want something with disaster recovery, par data and low latency, you simply have to roll your own. There is no other way.