I front a rock covers trio. The guitarist and I use these . . . http://www.wharfedalepro.com/Home/Products/POWEREDLOUDSPEAKERS/WPM1/tabid/407/Default.aspx
Have them mounted on a mic stand up close n personal. They won't take kick drum or bass, but if you just want them for monitoring vox then they're excellent, small and light. I must admit that we put them through an eq to get the best out of them, but even without the eq they're a great bit of kit. No good for FOH though.