Glenn Fleishman explains a tiny tweak you can make in Lion that enables AirDrop peer-to-peer file exchange to work over local area Ethernet and wireless networks. This enables AirDrop for older Macs that lack the right Wi-Fi chips to work with AirDrop out of the box, and it also adds wired LAN access for even those Macs that do have supported Wi-Fi chips. follow link
Set Password Activation Time in Snow Leopard
In Snow Leopard, you can now set an amount of time after your Mac goes to sleep or engages the screen saver before it requires a password to log back on. In Leopard, the option was simply to require the password or not. Choose among several increments, between 5 seconds and 4 hours, from System Preferences > Security.
Enable AirDrop for All Macs with Lion
Check out the Take Control ebooks that expand on the topic in this article: