you can identify the base, as well as the polarity by doing measurements (with a DMM in "diode check" mode). one lead will act as the "common" of what seems to be two diodes, and that's the base lead. reverse bias applied to the two "diodes" can identify the emitter, as one of them will act as a zener diode between 5 and 8 volts (this test should be done with a current limit of about 1 milliamp).
some common pinouts:
TO92 transistors
part number begins with 2N usually EBC across the front
part number begins with 2S (or just an A, B, C, or D) usually ECB across the front
part number begins with BA, BC, BD (i'm not as familiar with european types) CBE seems to be common
TO3P, TO264
most of these are all BCE
TO126, TO220
most of these are BCE
TO202
most of these are EBC
the main reason TO3P, TO264, TO126, and TO220 are BCE is that they are derived from the TO3 and TO66 packages, and in many situations can use the original TO3 or TO66 sockets without much trouble.
these pinouts are the most common pinouts, but there ARE exceptions (that's part of what keeps this business interesting)