Don't tell anyone, but I like going to hardward stores. If you or your clients have been considering new door hardware, take a look at this nifty little product.
I saw a demo on Kwiksets SmartCode Keyless locks that allows you to monitor and conrtrol door locks from you mobile phone or the internet. In addition to your regular access code, it allows you to create and share a code specifically for a scheduled access to you home such as when your expecting a showing or repair service. So you still have control even when you are not at home and monitor who has opened your door.
Check it out at Kwikset .