In search of indoor positioning device or sensors

Hi,

has anybody encountered some inexpensive way of getting positioning info
for indoor use (-> no gps receiving possible).

There are many accelerator meters like the Analog ADXL2xx series but =
their
error is to high
if you have the movement speed of a normal walker or jogger. (because of
temperature error=20
~ 2mG/C=B0)

TIA

/Marc