Do you like spark? Do you know Regex? Then you'll like this...
example:
bar --command "acpi" --regex "([0-9]{1,3})\%"
This will display something like this (in green):
[100%] ▇
if you want it to appear in your tmux, just put the flag --tmux in it:
bar --command "acpi" --regex "([0-9]{1,3})\%" --tmux
#[fg=green][100%] ▇#[default]
I will appear the same as the above if you're in tmux :)
I provide some examples (*.sh) like the one above for you to try and create your own ( and please pull request the new ones so we can all enjoy them ).