During displaying stats through Nginx parser I got such error very often:
----------
/Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/parsers/nginx.rb:15:in `parse': private method `split' called
for nil:NilClass (NoMethodError)
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/sources/ssh.rb:73:in `parse_line'
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/sources/ssh.rb:61:in `each'
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/sources/ssh.rb:61:in `parse_line'
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/sources/ssh.rb:88:in `do_tail'
	from /Library/Ruby/Gems/1.8/gems/net-ssh-1.1.4/lib/net/ssh/connection/channel.rb:496:in `call'
	from /Library/Ruby/Gems/1.8/gems/net-ssh-1.1.4/lib/net/ssh/connection/channel.rb:496:in `callback'
	from /Library/Ruby/Gems/1.8/gems/net-ssh-1.1.4/lib/net/ssh/connection/channel.rb:447:in `do_data'
	from /Library/Ruby/Gems/1.8/gems/net-ssh-1.1.4/lib/net/ssh/connection/driver.rb:323:in `do_channel_data'
	 ... 11 levels...
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/../lib/gl_tail/engine.rb:253:in `start'
	from /Library/Ruby/Gems/1.8/gems/gltail-0.1.8/bin/gl_tail:111
	from /usr/bin/gl_tail:19:in `load'
	from /usr/bin/gl_tail:19
-----------
So I've patch it a bit... Line 15 should be like:
    url = ''
    parameters = ''
    url, parameters = full_url.split('?') unless full_url.nil?

Now it works for me well.