play[1] and cog[2] used to be good, but it doesn't look like either of them have been updated in quite a long time...though the bitbucket repo for cog is showing some action, so maybe it will become active again at some point.

Vox[3] was also pretty decent last time I fiddled with it (quite a while ago).

[1]: http://sbooth.org/Play/

[2]: http://www.cogx.org/

[3]: http://voxapp.didgeroo.com/