[ShadowAce]

I like this one--I use it all the time:

GREEN='\[\033[32m\]'
RED='\[\033[31m\]'
NC='\[\033[37m\]'

PS1="\u@\w \`if [ \$? = 0 ]; then echo ${GREEN}:\\\)${NC}; else echo ${RED}:\\\(${NC}; fi\`"

[zeugma]

I like this one--I use it all the time:

Interesting. However, for colorblind folks like myself, there is not enough contrast. I may play with some color combinations to see if I can use this in place of the smiley/frowny