(CJ: Not comfortable seating tho.) Here's a video tutorial that shows you how to make your own inexpensive DIY outdoor bench using a few concrete blocks and some wood beams.
Concrete/Wood Planter Bench by Tao Concrete - modern - outdoor stools and benches - Etsy
Bench made from concrete and wood Beton-Gartenbank: Schritt 10 von 13
Elm and concrete coffee table- Concrete Pig
Quikrete's 5000 concrete mix is a great formula for building your own backyard bench.
rhubarbes: Designer Hilla Shamia Fuses Cast Aluminum and Tree Trunks to Create One-of-a-Kind Furniture Piece. (via Designer Hilla Shamia Fuses Cast Aluminum and Tree Trunks to Create One-of-a-Kind Furniture Pieces