In the same boat. I've been reusing the same General Logging Library so long it is still in a *.llb and seems fossilized.
My version is queue based with a handler that is started by calling the Startup method. Lets be clear that this is not OO based, or classes. The Methods VI is called with a "Logger Method" ENUM.
I have a few extra "Methods" beyond those mentioned by others above,
ENABLE / DISABLE - turns logging temporarily on/off
OPEN / CLOSE - The background Manager is also a GUI showing the last 20 events, a new event alert flasher with Ack button. Open/Close methods make the GUI appear and disappear.
The log files are closed and a new one opened on the first log entry after midnight, so each day has it's own log file.
Several things I'd like to add or upgrade, but it's fairly simple and as Rolf said, just works, so it's never been a high enough priority to rewrite or make OO. I've also used it "as is" on several RT apps, with no problems, but they were fairly slow RT, log rates of 100 mSec. If I had to log a lot faster I'd add in some number and lookup tables like Paul uses. Haven't needed it so far.
I've given quite a few copies away over the years, so I'll post it here.
(LabVIEW 8.2.1, if someone needs it I could probably dig further down and find 7.1 somewhere)GLOG_General_Log.llb