Perhaps your ethnicity would give you an idea? For example, I love Celtic music and instruments because part of my heritage is Celtic.
I also love Japanese music and instruments because I used to live there.
If you think of a country that has different instruments (Russia, for example) it will probably be much more interesting to you and your audience.
African slavery and the spread of jazz
European dance forms (or choose just two or three)
Evolution of the piano from the harpsichord
Influence of changes of philosophy and culture on music styles
I suggest going on National Geographic's website They have a world music finder. You can either do it by style (blues, rock, reggae, folk music are some of the more common ones on there), or you can search by place. You click on a continent and then click on a country you are interested in. While you do have to pay to download these songs, you can always just type in the artist for a free listen on you tube.
I recently did a project on African music which was very interesting. I searched African Music in wiki, and I got a good idea of some artists, like Ketil Kona, Afel Bocum, and the South African Children's Choir.
If you're looking for topics, here are a few ideas.
~National Anthems and how folk music of that country influenced them (try the Welsh National Anthem it is so beautiful)
~Throat Singing (try searching for it on you tube, it may sound very bizarre, but it is interesting).
~Comparing Fiddle Music of different European nations
~Unusual instruments like the balalaika and the Mongolian two-stringed guitar (I forget its real name)
Best of luck, have fun, and let us know what you come up with! I love this research topic as you can tell.