I'd like to do something that would really catch the attention of a college.
If you do things just for that criterion, then you will be living life backwards, and it will never end. Do things that you are curious about, are interested in, are good at. If you are an interesting person with cool experiences that matter to you, THAT will catch the attention of a college.
Please don't do volunteer work just for your resume. Using needy people for your personal advancement is really pretty low if you think of it.