DIY Cinder Block 'sofa': TI love how this cinderblock sofa almost takes on a kid-like quality. It's like it's built out of legos! I'd probably toss a cushion across the bench seat, but I love the plants organically growing out of the back.
Not with concrete, but maybe clay? Get the children involved with these cement stepping stones! All you need is some cereal boxes and quick drying cement. Decorate with glass stones. Excellent idea for the kids to get their garden creativity flowing!