Jeff has a nice post on that in his blog here. Also if you use wrapper class you can just create another variable there and display it as a first column.

Jeff has a nice post on that in his blog here. Also if you use wrapper class you can just create another variable there and display it as a first column.

Here is an example:

<apex:variable value="{!1}" var="rowNum"/>

<apex:dataList value="{!myCollection}" var="item">  
  <apex:outputText value="{!FLOOR(rowNum)}"/> - <apex:outputField value="{!item.Name}"/>
  <apex:variable var="rowNum" value="{!rowNum + 1}"/>
</apex:dataList>