What libraries should I use for MIME parsing, XML parsing, and MySQL ?

[John Levine]

I have a new application where people send me mail messages each of
which has an attached ZIP file. Inside the ZIP file is an XML file
which I want to parse and put the interesting bits into a MySQL
database. (This is the dmarc.org system, in case you were wondering.)

I'm running on FreeBSD which uses ruby 1.8. I see a bazillion ruby
packages in the ports collection, but it's not obvious which ones are
better than others. I figured out that Archive::ZIP is a reasonable
way to get stuff out of the ZIP file, but which libraries should I use
to:

* parse mail messages and extract MIME parts

* parse XML files

* talk to MySQL databases?

TIA