The purpose of this research study is to determine if the combination of sunitinib and gemcitabine is effective in treating patients with metastatic renal cell carcinoma. The safety of this combination will also be studied. Sunitinib is approved by the FDA for the treatment of renal cell carcinoma. However, some patients' cancers do not respond to treatment or stops responding after initially responding. Gemcitabine is a chemotherapy drug that is approved by the FDA for the treatment of pancreatic cancer and several other cancers. It is not approved for the treatment of renal cell carcinoma. Previous research has suggested that combining gemcitabine with sunitinib may have some effectiveness in treating metastatic renal cell carcinoma.