I use my first two initials and (married) last name for pretty much everything (my artwork, web design, writing) except as my "legal" signature. My married last name is incredibly common and generally neither mispronounced or misunderstood, so altogether my "pseudonym" would probably fit just about any genre as well as being gender neutral. I don't really use it as a disguise, I just really don't like writing out and I've never actually gone by Rebecca. All in all R.S. Robertson sounds both more mature and serious.
For a long time I thought about using my first two initials and maiden name as it is as uncommon as my married name is common. In fact, there is only one family in the United States with that name. The problem is that Wight,my maiden name, despite being spelled and pronounce just like right, tight, light, fight and sight, is ALWAYS mispronounce as Wig-hit for some reason, so it's completely useless as a pen name. Don't get me wrong, I really like my maiden name, I just hated having to constantly explain it to people. I once had a teacher call me a flat-out liar when I told him how it was pronounce... English teachers shouldn't require such intense pronunciation lessons from a 12 year old!