BSG uses Tcl extensively in-house and on projects. At BSG we do something called hybrid-mail. This means they take documents (mostly soft copy) and deliver them multiple ways (e.g. high volume printing/inserting & postage mail, email, fax).
Their biggest Tcl use involved building the USPS mailing online system [L1 ]. There is over 125k lines of Tcl driving the system (web site, document manipulation, scheduling, distribution, high volume printer controlling, postage mgmt, address standardization, mail prep and envelope inserting).
-- Todd Coram