I personally make my own .mp3 ringtones from songs or take snippets out of media that I find online with either programmes such as Nero Wave Editor using the Mp3 Pro plugin to make it extra small so it takes minimum space on a phone, also good becuase you can MMS smaller files. A free alternative to Nero is Audacity with the LAME codec or Wavpad with the LAME codec.

As for where can you get free ringtones, there are places such as www.mobile9.com and links from that website, mobile9 does have forums where I do understand you can request a particular ringtone to be made for you. It's more fun doing it you'reself though. I also make my own Themes for my handset, here's one I made earlier

Its all very simple to do really rather than pay for ringtones or themes, which in my opinion are rubbish when you can make better yourself