Is it possible to get research experience between undergrad and grad school? I will be graduating from my undergraduate with a B.S. in Computer Science &amp; Applied Mathematics with a ~3.25-3.30 in less than 2 weeks from now.  I'm taking at least gap year and a half after I graduate and am planning on applying to PhD programs in CS in the near future.  I have a semesters worth at my institution as well as an REU from this past summer, though I wouldn't say they are terribly related to what I may want to study towards grad school.  Aside this, though, I've looked at a couple other professors more towards my area of interest that I was considering trying to do research with (NLP/ML/Performance Analysis), but didn't, partly due to me taking three graduate-level courses this semester while finishing up my studies.  

I have debated working in industry vs. trying to bolster my application profile for when I apply, and want to be able to do research in the time between undergrad and graduate school.  I've seen this is common in fields like Bio/Neuro, but haven't seen too much for CS aside from a couple of positions in national laboratories, has anyone gone through getting post-bacc research in CS?
I spent a year as as a "research student" in Japan doing just that; for me it was between my Master's and Ph.D, but you can also do it after your undergrad.

Basically you need to find a school that offers such positions (here is where I did it), find a faculty member in that school whom you'd be willing to work under, and send them a friendly e-mail to ask whether they can host you.