diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,8 @@
+0.9.1.0
+-------
+- Added executeInteractive and executeInteractiveFallibly
+- Added envAt lens for tweaking the environment.
+
 0.9.0.0
 -------
 - All Siphon functionality has been moved to new package pipes-transduce.
diff --git a/process-streaming.cabal b/process-streaming.cabal
--- a/process-streaming.cabal
+++ b/process-streaming.cabal
@@ -1,5 +1,5 @@
 name:          process-streaming
-version:       0.9.0.1
+version:       0.9.1.0
 license:       BSD3
 license-file:  LICENSE
 data-files:    
diff --git a/src/System/Process/Lens.hs b/src/System/Process/Lens.hs
--- a/src/System/Process/Lens.hs
+++ b/src/System/Process/Lens.hs
@@ -5,6 +5,9 @@
 -- These are provided as a convenience and aren't at all required to use the
 -- other modules of this package.
 --
+-- For basic lens functionality with few dependencies, the @microlens@ package
+-- is a good option.
+--
 -----------------------------------------------------------------------------
 
 {-# LANGUAGE RankNTypes #-}
@@ -16,6 +19,7 @@
        , _RawCommand
        , _cwd
        , _env
+       , envAt
        , std_streams
        , _std_in
        , _std_out
@@ -79,6 +83,28 @@
 _env f x = setEnv x <$> f (env x)
     where
     setEnv c env' = c { env = env' } 
+
+
+{-| An improper lens to get and insert values in an association list. It
+    assumes that there are no duplicate keys in the list.
+
+-}
+envAt :: (Eq k,Applicative f)
+      => k 
+      -> (Maybe v -> f (Maybe v)) 
+      -> ([(k,v)] -> f [(k,v)])
+envAt key f [] =
+    let listize Nothing  = []
+        listize (Just i) = [(key,i)]
+    in
+    listize <$> f Nothing
+envAt key f (entry@(k,v):entries)
+    | key == k =
+        let listize Nothing   = entries
+            listize (Just v') = (k,v') : entries
+        in
+        listize <$> f (Just v)
+    | otherwise = (entry:) <$> envAt key f entries
 
 {-| 
     A lens for the @(std_in,std_out,std_err)@ triplet.  
diff --git a/src/System/Process/Streaming.hs b/src/System/Process/Streaming.hs
--- a/src/System/Process/Streaming.hs
+++ b/src/System/Process/Streaming.hs
@@ -27,6 +27,9 @@
         -- * Execution
           execute
         , executeFallibly
+        -- ** Unbuffered stdin
+        , executeInteractive
+        , executeInteractiveFallibly
         -- * CreateProcess helpers
         , piped
         -- * The Streams Applicative
@@ -140,7 +143,12 @@
 execute :: CreateProcess -> Streams Void a -> IO a
 execute cprocess pp = either absurd id <$> executeFallibly cprocess pp
 
+{-| Like 'execute', but 'std_in' will be unbuffered if piped.		
 
+-}
+executeInteractive :: CreateProcess -> Streams Void a -> IO a
+executeInteractive cprocess pp = either absurd id <$> executeInteractiveFallibly cprocess pp
+
 {-| Like 'execute', but allows the handlers in the 'Streams' Applicative to interrupt the execution of the external process by returning a 'Left' value, in addition to throwing exceptions. This is sometimes more convenient:
 
 >>> executeFallibly (piped (shell "sleep infinity")) (foldOut (withFallibleCont (\_ -> pure (Left "oops"))))
@@ -156,8 +164,25 @@
        CreateProcess 
     -> Streams e a
     -> IO (Either e a)
-executeFallibly record (Streams streams) = mask $ \restore -> do
+executeFallibly = executeFalliblyInternal (\_ -> return ())
+
+{-| Like 'executeFallibly', but 'std_in' will be unbuffered if piped.		
+
+-}
+executeInteractiveFallibly :: 
+       CreateProcess 
+    -> Streams e a
+    -> IO (Either e a)
+executeInteractiveFallibly = executeFalliblyInternal (\h -> hSetBuffering h NoBuffering)
+
+executeFalliblyInternal :: 
+       (Handle -> IO ())
+    -> CreateProcess 
+    -> Streams e a
+    -> IO (Either e a)
+executeFalliblyInternal adapter record (Streams streams) = mask $ \restore -> do
     (mstdin,mstdout,mstderr,phandle) <- createProcess record
+    forM_ mstdin adapter
     let (clientx,cleanupx) = case mstdin of
             Nothing -> (pure (),pure ())
             Just handle -> (toHandle handle,hClose handle) 
@@ -391,7 +416,7 @@
 
 {-| The type of handlers that write to piped @stdin@, consume piped @stdout@ and
     @stderr@, and work with the process exit code, eventually returning a value of
-    type @a@, except when an error @e@ interrups the execution.
+    type @r@, except when an error @e@ interrups the execution.
 
     Example of a complex handler:
 
diff --git a/src/System/Process/Streaming/Text.hs b/src/System/Process/Streaming/Text.hs
--- a/src/System/Process/Streaming/Text.hs
+++ b/src/System/Process/Streaming/Text.hs
@@ -63,7 +63,7 @@
     stream. We can do this with 'System.Process.Streaming.foldOutErr' and the 'Pipes.Transduce.combined' function.
 
     'combined' takes one 'Pipes.Transduce.Transducer' for @stdout@ and another
-    for @stderr@, that known how to decode each stream into text, then break
+    for @stderr@, that know how to decode each stream into text, then break
     the text into lines.  
     
     The resulting lines are consumed using a 'Fold1':