How to see the names of people that were recently in my vicinity

[ShiftyV]

I'm having issues with someone using alts to stalk me, and I'd like to know if I'm able to get the names of these avatars popping in for short periods on my land while I'm not looking/quick enough to get their names

[Rolig Loon]

Just install a "greeter" script in a prim on your parcel.  Almost any basic greeter script you can get in MP (or from free sites) not only welcomes visitors, it also stores their names or UUIDs.