You might have an Excel spreadsheet someone sent you with a list of Twitter accounts or some other document (a Google Doc, a text-file, etc.) and you want to create a list with all those accounts. Typically, this would be a very laborious process by going to each account and adding it to a list.
With Listpedia you can add hundreds of Twitter accounts at the same time:
If you have the accounts on multiple spreadsheets or documents, you can repeat the process multiple times. Listpedia will remove duplicates and update your Twitter List.