I think you know the dataSheets of commercially available Gas Gauge Chips like the bq series from TI, DS2746 and MAX1614 from MAXIM -- they also have some AN's on Battery/Power Management -- LTC4150 from Linear Technology, AT73C252 from Atmel, PS501, PS810 from MicroChip, NT1956/57 from Neotec, ZXCT1000 series from Diodes/Zetex ...