Most people I play with around here are mainly into doing open mic stuff, folky singer-songwriter stuff. So I was wondering whats an effective way of playing an electric bass with an acoustic guitar and maybe the occasional folky drummer?
I'm thinking a less is more approach, like a root at the start of every bar maybe?
How do you all do it?

roots, fifths, octaves, and simple runs (1/4 notes up or down to the next chord, especially in a change like verse to chorus)

thats how ive been doin it the last few years.

I would say it's no different, it depends on the song. There is some Jazzy hip-hop that is very cool with acoustic instruments and percussion. I would play some funky lines on that with a laid back feel. Traditional folk yes simple line or melodic bass if appropriate. Ask the who you're working with what they want or play a simple line and a busier line and let them say what they want.

I would focus on time and tone more. You are the source of time if no drummer so you have to be in control. Also you have to fill out the sound now is that a phat and smooth or more acoustic and percussive.

So never a simple answer have to listen and maybe chat up the songwriter about who they listen to get a clue to what they like.

Here is a guy I work with so you can hear what I do. I think the last two tracks are us live at an open mic and there is a video of us performing as well.

www.myspace.com/chrisgentryprojects

I pretty much play roots with funky accents on the fifth and octaved..

Hope this helps.

Listen to some of the stuff Jaco did with Joni Mitchell. He really helps the song without overplaying or getting in the way.