The Problem:
For hardcore daily fantasy sports nuts, there cannot be too much data. There are not enough sources that aggregate useful data in a meaningful way.
The Business
DailySplits.com
In baseball, splits are statistics for particular situations. For instance, best ERA during day games. Top ten hitters vs. left handers. Worst batting average when leading off after having hit 2nd or 3rd for more than 10 games in a row. The list could go on and on.
This information can help you excel in Daily Fantasy Baseball (a new site) and other daily fantasy sports. There are some sources out there that focus on daily stats and daily matchups. Examples include Daily Baseball Data, ESPN, Baseball-Reference and some others. However, there is no site that brings daily matchups, daily splits, and recent performance all in one place.
Doableness
Not outrageously difficult, but you do need to find a place from which to source the information. You also need to build feeds to capture then parse the data.
My Thoughts
As I have stated a few times before, I think daily fantasy sports are really climbing. I think they are about to hit mainstream. Right now niche players like Fanduel, DraftStreet, and a few others own the relatively small market. My belief is CBS, Yahoo and/or ESPN will be in this business within a year.