There are many options out there and a lot go good systems. The route I went is a little different than most people and probably cost a lot more than just spending time and making custom mounts/brackets. I decided to use OEM Audio+ speakers and DSP for the main sound set up and added two Alpine Type-Rs for the base. System sounds sick and I am pretty proud of how loud it goes since loud, clear, and high quality music is important to me. But this is what I have set up in my car at the moment. I hope to build a thread on it at some point.
-Stock pioneer headunit
-OEM Audio+ Reference series DSP w/ upgrade
-2 10" Alpine SWR-1023D subwoofers
-2 10" Integrity Concepts custom subwoofer enclosures w/ Hot Lava paint
-Alpine 1100w MRX-M110 amp
-Rockford Fosgate RFC10HB 10 farad Hybrid Digital Capacitor
-Kicker dual amp installation kit
-Girlfriend (SOLD =P)
Unfortunately I don't have larger pictures of my car at work but here are some small shots from my "garage" page.