Possible sources of presentation topics

Some suggestions, via John Wilkins at Ohio State University:

From Science, What we don't know: 125 top questions
    Intro and 25 questions
    100 more questions

Here are some recent new "physics ideas" in the last few years
    Physics News Update
    Physical Review Focus
    Physics Success Stories

Alternately, looking at what now counts as a great discovery over a longer time span might stimulate you with respect to recent ideas.
    Important inventions in the last 2000 years
    Greatest engineering achievements of the 20th century