Also, a proxychecker. In Haskell. Works as a filter, based on libcurl bindings

module Main where
import Network.Curl
import Control.Concurrent
import Data.Maybe
--import Threads

get proxy = curlGetString "https://twitter.com" [CurlProxy proxy,
                                                 CurlTimeout 5]

check curloutput = fst curloutput == CurlOK

thrputStrLn iolock string = do putMVar iolock 1
                               putStrLn string
                               _ <- takeMVar iolock