I work at SAP. I book absences via a web UI for a SAP system. I record my time using a very nice HTML5 UI that hooks into an SAP system via RPC. I record travel expenses in Concur (the company of the same name was acquired by SAP, so that counts as dogfooding too).

SAP still needs to get better at their dogfooding game in some areas (e.g. using our own ticket system products instead of internally-grown idiosyncrasies), but we're getting there.