The question is what inspires YOU. For me everything..beliefs, emotions, the people that sourround me, movies, things going on in the world, MOTIVATION. I think most importantly is the ENERGY you get off those things...what happened today that you really feel strongly about (something you probably disagree with)?? Write a few brief thoughts about it and then try to make it rhyme based on a riff that you think applies or is in the same mood or tone.
Also what you trully believe in, not some crap you think the concencious will want to hear. I think what ALL music is missing today, wether it be rock, metal, rap, pop, whatever, is a difference in opinion. Turn on MTV or your car stereo...everyone sings about politics and they all have THE SAME OPINION ABOUT EVERYTHING!! ie how many times in the past month have you heard "bring ur own bombs???" If someone wrote a pro war song, do you think they would play it?
Final Tip: Verrrrry important, if you do not have an adictave personality..don't be affraid to chemically enhance your emotions and you will write lyrics for hours!!! Or get me wasted and I'll write you all the lyrics you want lol!!!