You can put a great emergency roadside kit together in a coffee can. Get a can from home or work, clean it out, line it with a plastic bag from the grocery store and start putting your kit together. A #10 coffee can with a plastic lid is what is recommended. This coffee can kit will be able to get you out of most jams.
• One box cutter w/extra blades
• One can opener
• Two candles
• One cigarette lighter
• One compass
• One page of first aid instructions
• One notepad and a few pens
• Three matches
• Two plastic bags (1 kitchen/grocery-sized and one 30-gallon trash bag)
• One small sponge
• One sewing kit
• One hand towel (preferably a strainer cloth)
• One small roll of string
• One dust mask
• One Swiss Army pocket knife
• One roll of toilet paper
• One triangle bandage
• One pack of twisty ties
• One small roll of wire
• One small can of multi-oil
• One envelope with some extra cash and change
Once you get everything packed in, see how much extra room you have and if you wish, add some of the other items listed in the other articles here. This coffee can kit should cover just about everything, though.
Sources:
http://www.baproducts.com/coffecan.htm
http://www.quakekare.com/carprep2.html
http://www.survivalinstinct.com/aut.html
http://www.edmunds.com/ownership/howto/articles/43798/article.html