Wasn't there a vote to choose the name of Lois and Clark's child in S5?
TUFS may have done this -- I honestly don't recall -- but we in S5 decided amongst ourselves to have their child be a daughter named Laura Lane Kent.
Though despite what Julie said, I don't believe it's been commonly used in fanfic other than in S5/6 -- maybe you have read several S6 episodes and that's why it seems familiar? If so, I don't think that really counts considering the stories were written as part of a season. We weren't exactly going to be changing their child's name from episode to episode. <g> Oh, and incidentally, the name is not based on Lara, Clark's biological mother -- we all pretty much agreed that Clark has no strong emotional ties to them (especially following the NK fiasco) and we didn't think he'd name a child after either biological parent, especially not before honoring the Kents.
As for the popularity of the name CJ for L&C's son, there is one other reason for its use -- going on the assumption that this child will become Superman, many people have expressed the opinion that "Superman" and "Clark Kent" go hand in hand, therefore, any future Superman *must* be named Clark Kent (Junior, in this case).
Personally, I've always prefered "Jonathan Clark Kent" (Jon, Jonny) because it's fairly common and traditional to name children after a beloved grandparent, and both Lois and Clark are very close to the Kents. But I agree that, like CJ, it has become pretty ubiquitous in fanfic.
But as Annie said, I would vastly prefer any of the family names common in fanfic to the trendy names/spellings that some authors have used. In my experience, these stories tended to be written by younger authors, so maybe they were living vicariously through their characters. But I agree with Annie that Lois and Clark themselves would choose traditional names/spellings, whether or not they were family names.
Kathy