From RFC 1213 you could try sysDescr(1.3.6.1.2.1.1.1 ):
sysDescr
"A textual description of the entity. This value
should include the full name and version
identification of the system's hardware type,
software operating-system, and networking
software. It is mandatory that this only contain
printable ASCII characters."
The system section of 1213 has other interesting pieces of data like this too, like the sysObjectID (1.3.6.1.2.1.1.2.0):
sysObjectID
DESCRIPTION
The vendor's authoritative identification of the
network management subsystem contained in the
entity. This value is allocated within the SMI
enterprises subtree (1.3.6.1.4.1) and provides an
easy and unambiguous means for determining "what
kind of box" is being managed. For example, if
vendor "Flintstones, Inc." was assigned the
subtree 1.3.6.1.4.1.4242, it could assign the
identifier 1.3.6.1.4.1.4242.1.1 to its `Fred
Router'."