Sony-Ericsson has free software available from its website
(http://www.sonyericsson.com/support , then type in model number i.e. T230,
rather than selecting page with your region):
1. Sony Ericsson MMS Home Studio 1.1.273 - MMS composer for your PC that you
can then upload MMS to your phone
2. Sony Ericsson Image Editor 1.9.0 - Picture selctor that you can upload to
your phone
Obviously you need a data cable for these.

I called Sony-Ericsson (Australia) and asked about other software. They said
that as the T230 is a "low-end" phone it did not have software designed for
it as the "business" mobile phones did.

One piece of software that is worth investigating is floAt's Mobile Agent.
http://fma.xinium.com/

It seems no-one is keen to release ringtone software because then all those
websites and other that sell ringtones via SMS would lose business.

Xerxes
(Sony-Ericsson T230 owner)