second version of shiny app on https://groups.google.com/forum/#!topic/shiny-discuss/P74Ch8xHW_4

server.R

# server.R

shinyServer(
  function(input, output) {
    # table of inputs
    output$table.input <- renderTable(
      {input$data}
      , include.rownames = FALSE
      , include.colnames = TRUE
      , digits = 3
      , sanitize.text.function = function(x) x
    )
    # table of outputs
    output$table.output <- renderTable(
      {input$data^2}
      , include.rownames = FALSE
      , include.colnames = TRUE
      , digits = 3
      , sanitize.text.function = function(x) x      
    )   
  }
)

ui.R

# ui.R

library("shiny")
#library('devtools')
#install_github('shiny-incubator', 'rstudio')
library("shinyIncubator")

# initialize data with colnames
df <- data.frame(matrix(0, 1, 2))
colnames(df) <- c("First Column","Second Column") 

shinyUI(
  pageWithSidebar(
  
    headerPanel('Simple matrixInput example')
    ,
    sidebarPanel(

      # customize display settings    
      tags$head(
        tags$style(type='text/css', "table.data { width: 200px; }"
                                  , ".well {width: 80%; background-color: NULL; border: 0px solid rgb(255, 255, 255); box-shadow: 0px 0px 0px rgb(255, 255, 255) inset;}"
                                  , ".data { background-color: rgb(255,255,255); }"
        )
      )
      ,
      wellPanel(
        h4("Input Table")
        ,      
        matrixInput(inputId = 'data', label = 'Add/Remove Rows', data = df)
        , 
        helpText("This table accepts user input into each cell. The number of rows may be controlled by pressing the +/- buttons.")
      )
    )
    ,
    mainPanel(
      wellPanel(
        wellPanel(
          h4("Input Table")
          ,
          tableOutput(outputId = 'table.input')
          ,
          helpText("This table displays the input matrix in the side panel.")
        )
        ,
        wellPanel(
          h4("Output Table")
          ,
          tableOutput(outputId = 'table.output')
          ,
          helpText("This table displays the matrix obtained by squaring all cells in the input matrix")
        )
      )
    )
  )
)