plugin or script to move data from another program

I’m in the process of switching from a blog software that I wrote to WordPress. I’ve got 300 entries to move, and I’d like to find or write a script to do that for me. Can you guys recommend where to start? I’m an experienced programmer, so I’m not worried about learning another API. It would be great if you guys could point me in the direction of an existing script or plugin that I could modify to read in my data. Any ideas?