What chest exercises are available for people who don't have access to a pull-up bar or a bench/barbell? Are there any specific exercises that stand out as extremely good?
Wide Push-Ups; one of the best compound exercises available yet will isolate the width of the chest more so than a Close Push-Up. Combine both Wide/Close to target the majority of your chest.
Look at this : http://scoobysworkshop.com/chest-exercises/#pushups
There is plenty of good chest exercise in their, only requirement is dumbell ;)
I agree with what others have suggested. In addition, Pullovers are a great exercise for both the chest and back, done with dumbbells or a barbell. I regularly incorporate them into my chest training. There are several variations - flat bench/decline bench, and bent or straight arm.
Dumbbbell or Kettlebell Floor Presses are an oft-forgotten cousin of the much more popular bench press, and as the name suggests do not require a bench.
You could try flyes one-armed to test your stabilizing muscles and independently work both sides, personally I have found one-armed flyes to be very beneficial.