This thread shall abide here as a reference for just about any kind of speaker and sometimes audio work you want to do. If you have any links that you love, post up, and I'll edit the first post to include yours.
This is a site that links to MANY programs that are freeware and shareware. They deal with crossovers, testing speakers, designing speakers, testing rooms, and on and on. Starts out with Java calculators for tuning and other helpful box design tools. Then it gets to design and testing software downloads. It looks extremely useful, and has a ton of content.
This is a giant FAQ created and maintained by Ethan Whiner, designer of studios, and accomplished audio engineer and musician. The FAQ deals with much of the theory behind room acoustics, and gives MANY various tips and tricks related to minimizing room coloring of sound. Definitely recommended reading if you want to take the step beyond your components, and onto what really affects your sound.
And here is his forum where you can annoy 'the man' with your oft-asked questions.