Back in 2005, I had written a simple utilities to create custom event logs so many times that I decided to write one and release it under LGPL as a command line utility.
Recently (11/November/2014) I issued this as an open source project on CodePlex at https://commonmakelog.codeplex.com/.
It was necessary to release as an open source project rather than an executable as under Windows Vista, Windows 7 and Windows 8, it has to be run as administrator rather than just being run by an account with local administrator privilege.
It could probably be written in PowerShell.
Why create custom Event logs? If server side applications have their own custom event logs, fault diagnosis becomes that bit easier.