A combination of Zero X Loop Creator (do a search on the web) and Wavelab will make about any loop possible.
Wavelab has some of the best crossfade looping tools
Loop Creator is sort of a \"secret\" I\'ve been keeping and sharing with developers privately, only becuase I can possibly get a free lib out of it [img]images/icons/wink.gif[/img] )
It can actually Batch process files and batch create loops. Its all dependent on the file of course but supporting its developer (tell him Ashif sent you if you do buy it and his other AWESOME piece of software) will let him add new features. It works well with samples without alot of bass information. On samples with alotof bass info its possible to still batch process the files and create loops, but they need to be crossfaded which is batchable with other options, some I\'ve created with a combination of applications, and some thatare just in other applications.
Infinity is also a great tool if you have a Mac.
Also if you are looking to making more looping options for smaller samples, Melodyne will probably help.
anyhow, any sample developer not using wavelab 4.is missing out on a whole slew of functions that will help. Its quite simply amazing.