List of plugins to implement:

     iostat [-x] [-d] [-N] -zk [-p | <devices>...] <interval>
     SMART monitoring
     Solar position
     Xmonad
     Battery
     Volume control
     /proc/acpi (mute)
     System tray
     Eyes
     Launchers
     Taskbar (as in rarity)
     Application menu
     UPS
     Line reader
     Blueshift integration
     Backlight control
     hdparm
     Thermal monitoring
     ESSID and link quality for wireless interfaces
     News feed syndication
     Keyboard lock keys
     Keyboard layout
     EWMH
     /proc/interrupts
     /proc/net/dev
     /proc/net/sockstat
     /proc/net/sockstat6
     /proc/net/wireless
     /sys/class/net/<nic>/duplex (half, full)
     /proc/cpuinfo (cpu MHz)
     /sys/devices/system/cpu/cpu<index>/cpufreq/ (some parts requires root)
     /proc/sys/fs/dentry-state
         This file contains information about the status of the directory
         cache (dcache). The file contains six numbers, nr_dentry, nr_unused,
         age_limit (age in seconds), want_pages (pages requested by system)
         and two dummy values.
     /proc/sys/fs/inode-state
         This file contains seven numbers: nr_inodes, nr_free_inodes,
         preshrink, and four dummy values. nr_inodes is the number of inodes
         the system has allocated. This can be slightly more than inode-max
         because Linux allocates them one page full at a time. nr_free_inodes
         represents the number of free inodes. preshrink is nonzero when the
         nr_inodes > inode-max and the system needs to prune the inode list
         instead of allocating more.
     /proc/sys/fs/file-nr
         This (read-only) file contains three numbers: the number of allocated
         file handles (i.e., the number of files presently opened); the number
         of free file handles; and the maximum number of file handles (i.e.,
         the same value as /proc/sys/fs/file-max). If the number of allocated
         file handles is close to the maximum, you should consider increasing
         the maximum. Before Linux 2.6, the kernel allocated file handles
         dynamically, but it didn't free them again. Instead the free file
         handles were kept in a list for reallocation; the "free file handles"
         value indicates the size of that list. A large number of free file
         handles indicates that there was a past peak in the usage of open
         file handles. Since Linux 2.6, the kernel does deallocate freed file
         handles, and the "free file handles" value is always zero.