Rabin2 is able to find imported objects by an executable, as well as their offsets in its PLT. This information is useful, for example, to understand what external function is invoked by call instruction. Pass -i flag to rabin to get a list of imports. An example:
$ rabin2 -i /bin/ls |head
[Imports]
ordinal=001 plt=0x000021b0 bind=GLOBAL type=FUNC name=__ctype_toupper_loc
ordinal=002 plt=0x000021c0 bind=GLOBAL type=FUNC name=__uflow
ordinal=003 plt=0x000021d0 bind=GLOBAL type=FUNC name=getenv
ordinal=004 plt=0x000021e0 bind=GLOBAL type=FUNC name=sigprocmask
ordinal=005 plt=0x000021f0 bind=GLOBAL type=FUNC name=raise
ordinal=006 plt=0x00002210 bind=GLOBAL type=FUNC name=localtime
ordinal=007 plt=0x00002220 bind=GLOBAL type=FUNC name=__mempcpy_chk
ordinal=008 plt=0x00002230 bind=GLOBAL type=FUNC name=abort
ordinal=009 plt=0x00002240 bind=GLOBAL type=FUNC name=__errno_location
(...)