I have an old analogue modem hooked to our phone line, so when we receive an incoming call the number pops up on my computer screen (and the lounge TV screen if XMBC is being used at the time.) It is also cross-referenced with my address book so if it is a known number, it also displays the name of the caller.
One problem though is here in Australia, a lot of telemarketers, etc., have the caller ID comes up as private. Also, my mum, mother-in-law, sister-in-law and one of my clients all have private numbers, so that’s five likely sources when I see a private number. The problem is there’s only one of those sources I actually want to talk to (not saying which one, but it aint the telemaketers.)
Would love a device similar to the one cmdkeen mentioned available in the UK that will screen unknown numbers and voice prompt them.
I’ve occasionally pondered using Asterisk or similar open-source PBX to create a system like that. However it is in the queue behind about four other pet projects…