Harvard students in the sciences elect to pursue both research and non-research oriented positions after graduation. One popular option is to pursue one or two year lab research assistant appointments in academic laboratories. Those opportunities are typically posted on individual university/college human resource websites, so you may wish to target a geographic location and plan to regularly check those institutions' web sites in mid-spring. Otherwise, industry opportunities abound and can be searched using any of the following sites:
Life Sciences
Physics
Mathematics
Engineering
Biotechnology & Medical Devices
Technology & Electronic Gaming