Can I make my wood floors look nice?

I rent a 100+ year old duplex that has a original wood floor in the living room (constant high traffic area) and installing carpeting is absolutly not an option. The wood at one point was probably stained or sealed...I would guess many many years ago. The wood seems to have nothing on it anymore. If I ran my hand across it I would most likely get a splinter! I want to make it look nice, clean, and presentable with out it costing me a ton of $$$ as I only rent this place and the landlord will not reimburse me for my work. I guess that I would have to sand it which is fine but what do I do after? Also, when it rains my wood floor looks wet, spots everywhere! Is this going to make my work pointless? I don't mind hard labor I just don't want to spend alot on supplies. Any advise? I will try to answer any questions that are asked.