Dressing up in theme for Halloween is a fun family activity. The negotiating, brainstorming... its all a family bonding experience plus it makes for some cute pictures. Here's a few ideas from readers of what their families have had fun dressing up as for Halloween with their photos...
Movies are a great source of inspiration for Halloween costumes. The McVey family sent in this idea... to dress up as together as characters from The Wizard of Oz.

The McVeys also sent in the idea of dressing up together as "The Wild West."

Sophia Chiang-Qlubb sent in the idea of having a family of Jedis. Her family did this for a birthday party and put directions for making the costumes on her blog HERE. You can see a photo of her daughter in her Jedi outfit to the right.
My family and I did the Star Wars theme last year as well (see photo left). We made the adult costumes and bought the ones for kids.
Another idea for a family theme this Halloween: mom and baby animals. Amy Robbins-Wilson says she and her son did this last year and went as a mommy and baby jaguar.
You could also add to this animal theme by having someone in the family dress up as a zoo keeper while everyone else is an animal. My family did this several years ago for Halloween and we got tons of compliments. To add to the fun factor, my husband who was the zookeeper tied a bunch of stuffed animals onto his belt to add to his zoo!
Veronica McGregor sent in the idea of having the family dress in a shower theme. Her son Eli went as a shower a few years ago and she dressed in a bathrobe with col creme on her face. You could also add some little duckies to complete the theme with little tots.