I know most of you already know these apps or need something more advanced but I found them interesting so I thought I might as well share it here for those not familiar with them.
WARNING: one of the apps in the list (Plexamp) doesn't appear to be open-source so use it with caution.
I haven't used inkscape too much as it's always kept crashing on me and feels unorganized, but if you are already used to it I'm sure it's easier to just stick with it.