Take a couple minutes and add the year, engine and transmission, and transfer case to a signature and/or profile for future use on the forums. The quicker we know what it is, the quicker we can help.

Assuming its a 4.0L, start from the top and work your way down. The 4.0L sits at an angle so any leaks will eventually end up at the real main seal.

It could be any or combination of the following:

valve cover gasket
distributor gasket
oil filter adapter
oil pressure switch
oil pan gasket
rear man seal
front crank seal
timing cover

Doublecheck the transmission lines if its an auto. If they are leaking the fans, along with driving in general will blow the fluid around.

 

I would clean the area, let the vehicle run and watch it.... it might take some time but you might be able to identify it that way.

I work at a shop and they use engine oil dye, that is another option.

 

I'd start by seeing if you can tighten the oil filter up by hand. It's too much of a coincidence that it's leaking right about when you had it changed. I've heard horror stories about some of those oil change places (especially the big chain ones) - draining tranny fluid and then adding oil, stripped/over-tightened drain plugs and filter mounts, incorrect filters, etc, etc.
I'm sure there are plenty of great folks that do a good job that work at those places, but all it takes is one bone-headed teenager without proper training or skills to mess things up.

 

My kids XJ has had a slow leak for years. I'm sure its an old gasket somewhere. Just out of the blue the other day it started leaking a LOT when running... passenger side of center. I thought it was the oil filter adapter elbow which apparently can leak. It was the oil pressure sensor/sender right above it. Ours was pumping out oil when running Just got a new one today.