Not sure if your property is in CA or not, but the apartments I manage are and our prop mgmt co has us hold things of value that are left behind for 30-days and then donate to charity. 

STNL and MTNL is all I do nationally for clients day in and day out.   

I donate pretty heavily to charity, but my business is not a charity.

They also like new residential to be somewhat near retail or schools unless it is an enormous project where they might end up donating land for a new school.

I encourage people to donate to local charities, but agents never listen.

If they've left clothes and other belongings behind, you may want to document them and bag them up as the law does require storage of items for 30 days, at which point you can donate, sell, or throw away.

Depending on the type of loan you have, a lender can donate any underwater amount to the PHA, there is a possibility for tax benefits as well as credits under the Community Reinvestment Act.

It's also productive fun- I also like hobbies where I make things (knitting, sewing, cooking, fixing up things around the house, etc), but the sense of accomplishment at the end of spending 4 weeks solid knitting a scarf is not nearly as... well, fun... as spending that four weeks putting together a deal.And once you stop needing the money to live on, it starts going to interesting projects and things you care about- I try to donate money to science research I find interesting, but tends to get ignored by the big grant institutions- I could happily, happily, spend $100 million on that and never get bored.

You might as well donate it to a charity as it will get better use then buying junk!!!  

An old house was donated to our church, which didn't need the building, just the land.