Looks to me like you have received some great feed back. I have been a Property Manager for over 10 years. I have managed large upscale properties, student properties, section 42 properties, and now I am working with an investor managing his portfolio of rentals and rent to owns.
The pet fee is very effective, not only can you make some addtl. ancillary income, but it helps to protect you as well. Just remember, if legal in your state to definatley charge a pet deposit. My deposit is "non-refundable." You can also charge say a $300 deposit with $150 refundable.
You can also contact your local cable company. If you offer their cable service exclusively, sometimes you can get a percentage of the sales in return.
Be careful offering the anything with the word security in it. Sometimes, depending on the state, just using the word "security" can make you somewhat liable if something happens. But you can also check with the local alarm company, just have the charges billed to you, then charge you tenant..slightly over.
When filing evictions, I have in the past charged a $100 admin fee for having to go to the court house and file, in addition to the filing fees etc..
Also, if you have a multi-unit community, you can charge for faxing service, check with your local dry cleaners and set up a pick up and drop off service at the office.
You can charge extra for certain views, first floor, second, third etc...
Furnished units are good as well. You can contact a furniture rental company, and upcharge. These are especially profitable if you can get a company or two to lease a unit, especially for their out of town employees or guests.
Those are a few ideas. Please contact me if you want any more ideas..I have a ton! Everyone have a great day!