This weekend saw the first major tournament of new Standard, with Quiet Speculation's own Brian DeMars taking the whole thing down. The finals of the tournament pitted a pair of two-color decks against each other, though there was no shortage of decks exploiting the power of fetch+dual manabases. With two copies in the Top 8, you could make the argument that Jeskai Black was the most successful deck of the tournament.
Both decks are taking advantages of different strengths of the Jeskai base, but both players agree that Crackling Doom is a great reason to splash black. Jeskai has always been a little soft to Siege Rhino and other large creatures, and Crackling Doom allows the Jeskai player to deal with problematic creatures while also applying pressure.
This is just the tip of the iceberg when it comes to experimenting with new manabases and spell combinations. Gerry Thompson also made the Top 8 of the event with a five color list, and watching the metagame unfold will undoubtedly be very exciting. You can really just find the spells you want to play together and there will be a manabase that can support your idea. Be careful though, the red decks can and will run you over if you stretch yourself too thin.