diff --git a/Tools/TimePlot.hs b/Tools/TimePlot.hs
--- a/Tools/TimePlot.hs
+++ b/Tools/TimePlot.hs
@@ -106,6 +106,8 @@
                | KindCount     { binSize :: Delta t, style :: PlotBarsStyle }
                | KindLines
                | KindDots
+               | KindCumSum
+               | KindSum       { binSize :: Delta t }
                | KindNone
 
 
@@ -125,7 +127,7 @@
 
 readConf :: [String] -> Conf
 readConf args = case (words $ single "time format" "-tf" ("date %Y-%m-%d %H:%M:%OS")) of
-    ["num"]  -> readConf' (fmap (int2double *** id) . B.readInt)
+    ["num"]  -> readConf' readDouble
     "date":f -> readConf' (strptime (B.pack $ unwords f))
     _        -> error "Unrecognized time format (-tf)"
   where
@@ -172,6 +174,8 @@
         parseKind ["binc",    b,q] = KindBinCount  {binSize=read b, delims   =read ("["++q++"]")}
         parseKind ["lines"       ] = KindLines
         parseKind ["dots"        ] = KindDots
+        parseKind ["cumsum"      ] = KindCumSum
+        parseKind ["sum",     b  ] = KindSum       {binSize=read b}
         parseKind ("duration":ws)  = KindDuration  {subKind=parseKind ws, mapName=id}
         parseKind (('d':'u':'r':'a':'t':'i':'o':'n':'[':sep:"]"):ws)  
                                    = KindDuration  {subKind=parseKind ws, mapName = fst . S.break (==sep)}
@@ -260,6 +264,8 @@
       KindBinCount  bs vs -> withAnyOrdinate $ plotTrackBinCounts name es vs bs
       KindLines           -> withAnyOrdinate $ plotTrackLines     name es
       KindDots            -> withAnyOrdinate $ plotTrackDots      name es
+      KindSum       bs    -> withAnyOrdinate $ plotTrackSum       name es bs
+      KindCumSum          -> withAnyOrdinate $ plotTrackCumSum    name es
       KindDuration  _ _   -> error "KindDuration should not be plotted"
       KindNone            -> error "KindNone should not be plotted"
 
@@ -339,14 +345,20 @@
     toBars tvs = [(t,diffs vs) | (t,vs) <- tvs]
     diffs xs = zipWith (-) xs (0:xs)
 
-    plotTrackLines name es = layoutWithTitle (toPlot plot) name
-      where plot = plot_lines_values ^= [values es] $ defaultPlotLines
+    plotLines name vs = layoutWithTitle (toPlot plot) name
+      where plot = plot_lines_values ^= [vs] $ defaultPlotLines
 
+    plotTrackLines name es = plotLines name (values es)
+    
     plotTrackDots  name es = layoutWithTitle (toPlot plot) name
       where plot = plot_points_values ^= values es $ 
                    plot_points_style  ^= hollowCircles 4 1 (opaque blue) $ 
                    defaultPlotPoints
 
+    plotTrackCumSum name es = plotLines name $ scanl1 (\(t1,s) (t2,v) -> (t2,s+v)) (values es)
+
+    plotTrackSum name es bs = plotLines name $ byTimeBins sum bs t0 (values es)
+
     layoutWithTitle plot name =
         layout1_title ^= "" $
         layout1_plots ^= [Left plot] $
@@ -472,8 +484,8 @@
   "              x is only available if you installed timeplot with --flags=gtk",
   "  -or       - output resolution (default 640x480)",
   "  -if IFILE - input file; '-' means 'read from stdin'",
-  "  -tf TF    - time format: 'num' means that times are integer numbers less than 2^31",
-  "              (for instance, line numbers); 'date PATTERN' means that times are dates",
+  "  -tf TF    - time format: 'num' means that times are floating-point numbers",
+  "              (for instance, seconds elapsed since an event); 'date PATTERN' means that times are dates",
   "              in the format specified by PATTERN - see http://linux.die.net/man/3/strptime,",
   "              for example, [%Y-%m-%d %H:%M:%S] parses dates like [2009-10-20 16:52:43]. ",
   "              We also support %OS for fractional seconds (i.e. %OS will parse 12.4039 or 12,4039).",
@@ -502,8 +514,6 @@
   "  'duration[C] XXXX' - same as 'duration', but of a track's name we only take the part before character C.",
   "     For example, if you have processes named 'MACHINE-PID' (i.e. UNIT027-8532) say 'begin something' / ",
   "     'end something' and you're interested in the properties of per-machine durations, use duration[-].",
-  "     An interesting combination is, for example, duration[-] cumsum - you'll see total durations of the",
-  "     something for all pids on a machine, for each machine.",
   "  'hist N' is for histograms: a histogram is drawn with granularity of N time units, where",
   "     the bin corresponding to [t..t+N) has value 'what was the maximal number of active events",
   "     in that interval'.",
@@ -519,10 +529,10 @@
   "     into bins min..v1, v1..v2, .., v2..max in time bins of size N",
   "  'binc N v1,v2,..' (example: binf 100 1,2,5,10) - a bar chart of counts of values falling",
   "     into bins min..v1, v1..v2, .., v2..max in time bins of size N",
-  "  'lines' - a simple line plot of numeric values",
-  "  'dots'  - a simple dot plot of numeric values",
-  "  'sum N' - a line plot of the sums of numeric values in time bins of size N",
-  "  'cumsum' - a line plot of the cumulative sums of numeric values seen so far",
+  "  'lines'  - a simple line plot of numeric values",
+  "  'dots'   - a simple dot plot of numeric values",
+  "  'cumsum' - a simple line plot of the sum of the numeric values",
+  "  'sum N'  - a simple line plot of the sum of the numeric values in time bins of size N",
   "N is measured in units or in seconds."
   ]
 
diff --git a/timeplot.cabal b/timeplot.cabal
--- a/timeplot.cabal
+++ b/timeplot.cabal
@@ -1,5 +1,5 @@
 Name: timeplot
-Version: 0.2.4
+Version: 0.2.5
 License: BSD3
 License-file: LICENSE
 Copyright: Eugene Kirpichov, 2009