My current swap usage is 0, so I guess it's not that useful to have :P

I haven't bothered to create a swap file on this laptop yet. I haven't gone below 200MB free...

Oh, and fragmentation in the filesystem of your swap file doesn't even have that much of an effect. Contiguous pages in a processes memory are not necessarily placed contiguously in swap (nor necessarily retrieved from swap consecutively). So that extra seek time that fragmentation causes would be present already.