I'm getting so sick of these threads. Seriously, if you don't have an idea of what you want a texture pack to look like then why do you want to make one?
OK, ok, not helping.
You want an idea for a texture pack? I'll tell you the same thing I tell EVERYONE who posts here looking for an idea: pick something that you love and make a pack based on it!
What kind of music do you listen to? Classic Rock? Swing? Power Ballads?
How about TV and Movies? What genres do you get into? Horror? Sci-fi? Romantic Comedies?
What are movements do you like? Art Deco? Renaissance? Modern art?
Or maybe you're inspired by your activities? BMX biking? Religious activities? Hanging out at the mall?
Find something that you enjoy. Something that you enjoy enjoying. Something that you love to put your heart and soul into. The one thing about yourself, and your relationship to the world outside of yourself that fills your heart with glee! Make a texture pack based on THAT! Make it the pack of choice for people who also like that thing. Let your love shine through, and inspire those who see it.
And heck, it doesn't even have to be one thing. Pick a couple. Pick one thing from everything you love and do the entire pack one block at a time. Sure it'll be eclectic, but it'll be YOUR pack. A work of art that represents YOU as a person.
That's the idea: Pick something your passionate about and make a pack based on that. There you go.
(So far nobody I've said this to has ever made a texture pack. Try to be the first, because at this point I feel like I'm wasting my time)