The Newberry Library has Everywhere West: Preserving and Enhancing Access to the Records of the Chicago, Burlington & Quincy Railroad Company. The site includes an informative blog; project manager Alison Hinderliter recently posted about using CB&Q land records to track a Swedish immigrant in Iowa. The collection itself covers a wide variety of corporate records from 1840 to 1965 and occupies more than half a mile of shelf space.
Comment: This project would not have happened without a grant from the National Endowment for the Humanities. And that in turn would not have been possible if the CB&Q land records had not been recalled from Harvard University's Baker Library in 1946 and placed at the Newberry instead. For those who don't know, Baker explicitly excludes all genealogists as non-scholars. I trust that those choosing where to donate money and historic papers will treat that institution as it treats them.