Linux-Powered, WiFi Handheld?

rgovostes asks: "I've been looking around for a (hopefully low-cost) Linux-based handheld device with WiFi capabilities for some network testing and security evaluation. I need to be able to ping, list nearby WiFi signals, and run Ettercap. I'd also like it to be Mac OS X compatible without much work. I found handhelds.org (Coralized), which has some information, but I'm not very handheld-savvy, so it isn't too helpful to me. Am I asking for something unrealistic or is something like this possible? Any advice on the matter would be appreciated."