I've actually began work on two stories with Clark being a single dad.
Story one: Clark had a relationship with Lana six years before the pilot. Lana dies due to complications of childbirth after giving birth to identical twin girls.
When Clark moves to Metropolis, the girls stay in Smallville with their Grandparents, since Clark had moved them many times during his travels; and Martha and Jonathan thought it would be good for the twins to be in one place for a while and make sure Clark intends to stay at the Daily planet.
The story pretty much follows the plot line of the show with tha addition of the two girls.
In the second story: At a young age (10-14) Clark's differences were discovered and he was taken away from the Kents to be studied. His children were created using Clark's DNA. The results of that experiment is one boy and two girls.
Clark submitted to the testing on his body for years, until the kids became the subject of the experiments. Using his strength, Clark demolishes the lab; takes his kids and flees. Blending into normal scoiety as best as they can, Clark tries to create a life for his kids; and eventually makes a home in Metropolis and the Daily Planet.
Lois is initally curious about her new partner and eventually learns about his early life. Thinking it might be Pulitzar material, Lois decides to investigate the agency responsible for Clark and the childrens' captivity. and in true Lois fashion gets in over her head and needs Clark to help her out.
Unfortunately, this is about as far as I got with these plot lines so if anyone is interested in adopting them let me know.
