OUTLINE: Donors receive filgrastim (G-CSF) subcutaneously for 4 or 5 days prior to peripheral blood stem cell harvest. Patients are assigned to one of three conditioning regimens, depending on disease. Group A (small cell lung cancer): Patients receive cyclophosphamide IV over 1-2 hours on days -7 and -6, etoposide IV over 4 hours on day -5, and total body irradiation twice daily on days -4 to -1. Group B (breast cancer and testicular germ cell cancer): Patients receive oral busulfan every 6 hours on days -7 to -4 for a total of 14 doses. Patients then receive cyclophosphamide IV over 1-2 hours on days -3 and -2. Group C (renal cell cancer and melanoma): Patients receive fludarabine IV daily on days -8 to -4 and cyclophosphamide IV on days -3 and -2. All groups: Patients receive allogeneic peripheral blood stem cells IV over 10-20 minutes on day 0. Patients are followed weekly for 3 months, at 6 and 12 months, and then yearly for 5 years.