What do you keep on hand for sudden sewer backups?

I do keep some bleach on hand for really bad jobs (think raw sewage), but I use it sparingly and ventilate like crazy.

Yeah, I learned the hard way about ventilation after a backup in my old place—thought I was being smart with bleach, but ended up with a pounding headache and had to air out the whole basement for hours. Now I keep a box fan stashed just for emergencies. Also, those heavy-duty rubber gloves are a must... found that out after ruining a pair of dish gloves. Live and learn, right?