Suppose you have a list of URLs that your client has given you. Now suppose they also have stored the text for each URL in a seperate column alongside the URL. At first it might seem difficult to get this into a Hyperlink field on a SharePoint list, especially since the UI for the Datasheet view does not allow for each updates to these two pseudo-sub-fields seperately. You might be tempted to enter them both as simple text fields and use a calculated field and a data view (or some other nonsense) to get what you want. Don't, because it's actually quite easy.
Instead, bring your columnar data into Excel. Then in a blank column, use the HYPERLINK(url, text) formula to generate the links. Reference the calls to each column respectively within the formula. When you copy these into a SharePoint datasheet view, the text of the links will be preserved. Violla!