If you are going into your senior year, then you have time to pick a couple of classes to help you here. If you have some reasonable software experience then taking a CS class isn't necessary, but if you are not comfortable programming then I recommend taking a good intro class.
I am an engineer, and I have interviewed a fair number of math and physics majors. Where I work we do a lot of signal processing algorithm development, as well as build prototype systems to obtain the data we need for that. So basically we do R&D (other parts of the company build real things). We like to have folks with a variety of backgrounds to keep fresh ideas coming in. I cannot speak in general for all jobs ofcourse, but if that kind of work sounds interesting I can tell you what classes I want people to have:
1. some programming course or equivalent experience. Everyone writes some software, and right out of school that is usually the easiest way for new hires to earn their keep while they get up to speed on the rest of the stuff. I have never interviewed someone who didn't have this.
2. Linear algebra. You must have taken this already, and your experience with quantum mechanics probably makes the subject more alive for you. Believe it or not there are still some engineering schools that allow students to not take this, which should be criminal!
3. Probability theory. Everything we do is statistical - knowing statistics and/or stochastic processes would be good too, but probability theory is the foundation. For some reason many physics students (including grad students!) never take probability. The ability to think probabilistically is useful for anyone in a technical area, whether you go to grad school or get a job.
4. Signals and systems - this is the one course to take to make a physicist (or mathematician) think like an electrical engineer. Every EE department teaches this. On the surface it is just applied Fourier analysis, both continuous and discrete, but learning to think in both the time and frequency domains is key. DSP, communications, etc., are all easy to understand with the tools from this one course. I recommend it if EE kind of jobs are at all interesting to you. This is not a hard course, just an important one!
5. This is more of a wish than a requirement, but I like folks who have a solid understanding of electromagnetic theory, especially waves. Everything today is wireless, and occasionally having a good feeling for waves and radiation is useful. you should have this sewn up!
My guess is that items 1,3 and 4 may be holes, if you are interested in these sorts of jobs. If I had to pick two, I'd pick 1 and 4. Physicists usually have reasonable intuition for probability since they learn a little in statistical physics, so learning on your own isn't too bad.
This is just one perspective, others will have additional info for you.
Good luck,
jason