Describe Picklist

Code:

    public List<SelectOption> EconomizerMakeSelectOptions { 
     get {
      List<SelectOption> options = new List<SelectOption>();
      Schema.DescribeFieldResult dfr = Unit__c.EconomizerMake__c.getDescribe();
      List<Schema.PicklistEntry> ple = dfr.getPicklistValues();
      for (Schema.PicklistEntry a : ple) {
       options.add(new SelectOption(a.getValue(), a.getLabel()));
      }
      return options;
     }
     
     set;
    }

Source: 
In Apex: 
http://blogs.developerforce.com/developer-relations/2008/12/using-the-metadata-api-to-retrieve-picklist-values.html
Using Javascript: 
http://demandchainsystems.blogspot.com/2008/04/create-dynamic-picklist-in.html