Is there any sort of a ground shuttle between LAX and SNA or LAX and BUR, other than the standard L.A. public bus lines? Thanks for any info.

There are a bunch. This link (http://www.airwise.com/airports/us/LAX/LAXtran1.html) lists them with their phone numbers. The two most popular ones seem to be Super Shuttle and Prime Time Shuttle. You can call most of them for free from the phones near the baggage claim area at LAX. I think you're going to pay somewhere from $20-$30 for a one way trip.