When you talk about neutral, I assume you are speaking of "junk" DNA. If so, don't be so quick to assume it is useless. I think the jury is still out on that one.
As an example of a neutral mutation, I have a disorder called keratoconus (
http://www.kcenter.org). While the exact causes of it have yet to be fully investigated there is an known genetic component. This disorder would eventually lead to blindness on my part, 2 cornea tranplants (and waiting for a third) will hopefully take care of this. Keratoconus usually doesn't affect the individual until the beginning of puberty and then it is a gradual process. Because of this the individual is not disadvantaged in respect to passing on his (keratoconus almost always afflicts males) genes. In the long run left untreated this disorder would be leave the individual highly disadvantaged but in terms of simply surviving to reproduce this mutation is overall neutral.
*not an actual doctor