Hi! Yeah, the internet and websites have helped in this regard quite a bit, as far as "common law copyright" is concerned. mp3.com, or even if you have your own site, once it is "public," it adds more to a "claim" if ever needed. For around $30, a legal copyright following the correct procedures is that extra bit that could make a court visit go in your favor. Picture heading into court with a $100/hour lawyer and facing some idiot that has a team of lawyers that some label is paying to defend them.
Another thing is this: Say you write a song, or group of songs. People close to you at the time later claim they helped with the writing of the song(s). One of them happens to have received an inheritence, and can afford to spend time in court. With the proper procedures followed, and proper paperwork filed, there is quite a bit less room for doubt, or interpretation.
Personally, what I do is create a cd of work. That cd will include songs that I wrote, no one else. Then, copyright the group of songs as a work. If I need to seperate them at a later date, it is legal to do so, and since I own the copyright on those songs in their entirety, I am legally allowed to split the songs from one another and release them (or perform, license, etc), since it is my OWN copyright on the original works. $30 for say 10 songs? WELL worth it. Cannot stress enough- in this day and age, it is just safer to use this relatively inexpensive way to fully and legally protect yourself and your work!
I spend some time each year reviewing stuff like this, looking for any changes, and trying to learn a bit more. Recently it was trademark law. Trademark law is a bit more complex, and something I would recommend involving a lawyer or a legal group that specializes in that. Plus, some of the links I put in last post have some pretty good info on recording contracts and some typical pitfalls and stuff to look out for. Beware tho- dig in deep enough, and you may never want to sign with a "major" label. Ever. Can take every ounce of fun out of music.