Use Leadpal to mass convert leads into accounts and contacts. Now you can mass assign Accounts while converting leads.
Here are other features of Leadpal
1) Connect on Linkedin with the Lead.  News about the company from Lead
2) Grab Company Information to Lead.  For example our screen would display on the lead from Salesforce.com
Company Description: Salesforce is the Customer Success Platform. Our social and mobile cloud technologies—including our flagship sales and CRM applications—help companies connect with customers, partners, and employees in entirely new ways.
Employee Count:10000+
Type: Public
Industry: Internet
This feature is useful as some companies only want to work with companies where employee count is greater than 150
3) Import Linkedin Connections as Leads
4) Post to Linkedin Groups with a single click
Take a free trial at https://appexchange.salesforce.com/listingDetail?listingId=a0N3000000B5LuWEAV