I'm thinking about minoring in psychology.
I'm going to major in biology..
I know that my app will look better if I have a minor.
However, I'm not sure if it would be "worth it" to spend extra time and money to get a minor degree.
I could be way off base, but I'm fairly certain nobody outside of the world of undergraduate education cares about minors...I wouldn't count on a minor to make your application shine.
The quick and dirty answer is: sometimes. The longer answer is: it will possibly help you in the real world if it's a minor with potential for application on the job or if it's really offbeat or contrasting with your major. Computers, business, (relevant) languages, etc. I don't really think psychology fits the bill, though you might use a little psych 101 in dealing with patients at times. It's hard to imagine an admissions committee being especially impressed by a psych minor.
Some minors open up things for you though like internships. here at my college, there is a biotechnology minor and it allows you to do an industry internship for biotech with bio or chem focus. I'd do it for the work experience and potential job. There is another in entrepreneurship as well.
In my opinion, the amount of coursework required for most minors doesn't really prepare you to do anything (or at least much) in that field. But, if it is something you're interested in, and if you need the elective hours anyway, then go for it.