Well, depending on your institution and how liberal they are on stacking double majors, you can make the case that you went back to school for another major, and take classes for those, while deciding to "minor" in something interesting that may have a specific bias to having higher grade distributions.
Here's an example. At my institution, if you qualify for one full degree, all you need is 25 hours in another discipline (there is a list of acceptable disciplines to do this with, some are allowed with this 25 rule, some aren't), and you also get the degree for that discipline as well.
I have a friend that qualified for a full BA in Biology. She took 25 extra hours in Psychology, as well as 12 more hours in Sociology (she split the 37 hours into 6 hours over the summer, 15 hours in the fall, 3 hours in the Winter session, and 13 hours in the Spring). She made a 4.0 in that part of her major and it raised her GPA as she claims from 3.63 to 3.82. As a result, in 5 years, she got a BA in Biology, BA in Psychology, and minors in Sociology and Spanish (her BA in Biology gave her flexibility to choose Spanish classes as her liberal arts electives under her BA in Biology). Her sGPA stayed the same though because those classes weren't Biology, Chemistry, Physics, or Math as made standard as science GPA qualifiers by what I believe to be (don't hold me on this) the AAMC.
However, since Chemistry is an acceptable list of those majors, it gives you an opportunity to simultaneously raise the science GPA as well as the Cumulative GPA. It can also decrease it though, so beware.
Check with your institution if they offer any remotely similar to this.
Also, I don't know if taking those classes at community colleges is advised. It makes it look like you regressed in the academic hierarchy with no direct benefit (considering after you graduated, those CC classes aren't explicitly applied via transfer in hopes of achieving a secondary degree) and only chose those classes for self gain in terms of GPA, unless it was in some field like say, Art History or Math or something that you just wanted exposure to for self learning and enjoyment without paying big bucks at a university, and could take maybe a 4-5 class stretch or sequence at a CC. Then you could possibly justify with an adcom or something on why you took those classes.
