If you really want a challenge
I have played electric bass as well as string bass since the late 1970s. I would suggest finding certain songs that you like and breaking them down in segments. Tape KGGO, The BUS, KIOA or something like that for an hour or so and there is a good chance you will find something that you like, then you can play the tape of those songs and go back to catch certain parts again. Use a smaller speaker for listening to bass within the songs-6" or 8" versus large 12" or 15" woofer, too hard to break it out of the other deep sounds.
Hopefully you have played long enough you know the fundamentals, taking care of this first is where I would suggest all new players to emphasis for the first few weeks to months as well as taking lessons. 1970s songs and yes everyone will laugh: disco and other easy listening songs of the that time period generally have great bass studio players and bass lines that help give the listener an understanding the importance of bass and structure of songs with timing, chords and octaves, and progressive changes just about better than anything else. Simple progressive blues songs are also a good start. Start with the basics and work up.
[ame=http://www.youtube.com/watch?v=6O9zMnwD65Q]YouTube - Cliff Burton Solos[/ame]
Some one mentioned RUSH earlier, and I would agree there are some great bass lines in their songs. A recent instrumental song that they were nominated for best instrumental for is "Malignant Narcisism". It is a pretty awesome bass song. You can find a video for it on YouTube. I am too lazy to link it though.
Muse has a ton of good songs. "Hysteria" is one of my favorites and has a great bass line. There is a good YouTube video out there for this as well.
Check out Jaco Pastorius and Weather Report.
Steve Harris has played some pretty cool stuff.
Check out some of the old Motwon tunes as well!
Anything by Primus, Rage Against the Machine, or Kyuss.
Primus- Greet the Sacred Cow
[ame=http://www.youtube.com/watch?v=Ni-WNpEfsjs]YouTube - Primus - greet the sacred cow[/ame]
For good bassists to listen to, Victor Wooten (alive). is really really good, in fact he has a music camp. Jaco Pastorius, RIP, was one of my favs until he was beaten to death back in the 80s. For really active bass lines, a number of Steely Dan songs have them, Geddy Lee with Rush always does a lot; so go out and nail Tom Sawyer if you haven't already. I always fire up the amp if that song comes on the stereo.
[ame=http://www.youtube.com/watch?v=F47nSQuDfnE]YouTube - Stuart Hamm - Charlie Brown Theme (Linus and Lucy)[/ame]
[ame=http://www.youtube.com/watch?v=hifMG_ueKnc&playnext_from=PL&feature=PlayList&p=50F916A083852C8F&index=18]YouTube - Racer X - Scarified (Mario Garcia - Dark Moor)[/ame]
[ame=http://www.youtube.com/watch?v=isFPCMAcPZM&feature=related]YouTube - Racer X Scarified 1988[/ame]