This base above was done by using extra bits. He cut them up painted them and then put them on the base. He gave a wash of red ink for more gore. Even without red ink you can still achieve a gore look depending on what reds you use.
This base is a nice example because it is a flying base. Flying bases are clear so many people including myself don't base them. I do not base them really because I never know what to do with there curved surface. What he did was first flocked and painted the base. Then he took pink insulation foam and cut square pillars out of them. He then cut the pillars tops angled to give a crystal appearance. He then painted highlighted and glossed them for a shine. Crystals can be any color so the exact colors do not matter here.
Here is a nice example of base combination. A square type base and a round base to give a small diorama quality to it. For purposes of gaming you could just do all measurements to the beginning of the round base and ignore the square one for purposes of charges or range for weapons. Also you could potentially work the dead terrain feature underneath your model (depending on what it is) to keep it as one base for those really rule oriented gamers. What he did was take a spare marine and a spare skeleton model and fused the two. He then used wires to give the effects of ripped apart armor. Paint and add any blood effect and your done. This could also be done with imperial guard or any race really. The base behind this one was done with pink foam cut randomly to resemble rock. Also some scoring was done for a more eroded feel. It was then based black and dry brushed codex grey and then fortress grey followed by a light touch of white. He added pins to the models feet and pressed them in with glue to secure the model to the foam.
Lastly a ripper swarm base. The nice thing about ripper swarms and other swarm bases from GW is that there is a decent amount of space to allow a simple base job to add narrative. He flocked the base and painted the skeleton model separately. He then attached the skeleton to the base and coated it with red ink. Afterwards he positioned the rippers to appear like they just finished feasting and were moving on. A note here: rippers and scarab swarms are a special case in which you could make a base that would take your eye initially away from the models themselves. That is ok because these bases represent swarms of tiny creatures. It adds a lot to the base regardless of if your eye is not drawn to them directly from the beginning. Sort of like " hey its a dead guy.. oh rippers are coming" type of thing.
So there you go. 4 different examples of bases that are not hard to do and would not take away from the models themselves. More to come in the future of this and other stuff. Until then.