I discovered isit via pyhn while making a video for it, it looks quite interesting, because it provides many information, from help(isit) on my machine, behold:

__version__ = '0.3.2'
april = False
archlinux = False
archlinux_release = None
archlinux_version = None
august = False
autumn = False
big_endian = False
bit32 = False
bit64 = True
centos = False
centos_release = None
centos_version = None
cpython = True
debian = False
debian_release = None
debian_version = None
december = False
elementaryos = False
elementaryos_codename = None
elementaryos_release = None
elementaryos_version = None
february = False
friday = False
heroku = False
home = False
hpux = False
in_git = False
ironpython = False
january = False
july = False
june = False
jython = False
linux = True
linux2 = False
linux3 = True
linux_version = u'3.12.13-gentoo-1'
linuxmint = False
linuxmint_codename = None
linuxmint_version = None
little_endian = True
march = False
may = True
monday = False
newrelic = False
november = False
october = False
osx = False
osx_version = None
package_deb = False
package_rpm = False
py2 = True
py24 = False
py25 = False
py26 = False
py27 = True
py3 = False
py30 = False
py31 = False
py32 = False
py33 = False
py34 = False
pypy = False
redhat = False
redhat_release = None
redhat_version = None
saturday = True
september = False
solaris = False
spring = True
summer = False
sunday = False
thursday = False
tuesday = False
ubuntu = False
ubuntu_codename = None
ubuntu_lts = None
ubuntu_release = None
ubuntu_version = None
virtualenv = False
wednesday = False
weekend = True
windows = False
winter = False

It has no functions, just a huge group of module attributes, that you can check if certain thing is True, for examples:

>>> isit.linux
True
>>> isit.linux_version
u'3.12.13-gentoo-1'

Frankly, the code is kind of scary to read, like a giant spaghetti dish.

isit is written by Geoffrey Lehée under the MIT License, currently 0.3.2 (2013-06-08), for both Python 2 and 3.