I prefer the go-anywhere no net required one by Josh Maddison. You can add you own custom conversions too so if ever you need to convert metric ***-loads
(TM) to the more generic common shit-loads its your program.
http://www.joshmadison.com/software/convert/
now what was the AL to SL converion factor again.
Another useful conversion is actual RWKw to unstubstantiated net RWKw where I think the factor is .74.
enjoy