I cannot think of anything for Linux as good as Belarc Advisor. Even
my Solaris box requires running a number of programs; see:

<http://thadlabs.com/FILES/sysconfig.txt>

Some info can be gleaned from /proc if you cat some of the items there.

Believe it or not, there are two things from Sun that do characterize
a hardware platform, and I used one of them (install_check, an ISO for
a bootable CD) that I took to stores before buying the system detailed
above in sysconfig.txt); if you're interested and/or curious:

<www.sun.com/.../install_check.jsp>

The install_check ISO is 74MB. A similar Java device detection tool
is here:

<www.sun.com/.../device_detect.jsp>