The Ring Nebula has a very nice set of data. It's very fun without a lot of odd things to deal with. I included the faint outer structures which resemble petals of a carnation but they are a bit underexposed and blurry. You can see them better <a href="http://hubblesite.org/newscenter/archive/releases/2013/13/image/a/format/large_web/" rel="nofollow">here</a> in an image which combines Hubble data with imagery taken from the ground.

Red: hst_07632_01_wfpc2_f658n_wf_sci Green: hst_07632_01_wfpc2_f502n_wf_sci Blue: hst_07632_01_wfpc2_f469n_wf_sci