Cheap car-cams are all over ebay - for about £30 + sd card, you can get motion activated, hd cams with substantial lithium batteries and a range of features. Some are crap, some are awesome - use common sense when sorting through ebay... Most can also chop (e.g. 1 hour blocks) and cycle (e.g. auto-delete oldest). Depending on your quality settings, sd card size etc, you may be able to leave it until there is something dumped (as long as you check and recharge / replace battery occasionally). Beware of trees though - wind can trigger motion sensors and easily eat up batteries.

How about Nasa and Google ( or another interested business/third party) come together and make a complete, consistent, as-detailed-as-hubble map of the sky? Like Google Sky, but with consistent snaps of the quality that would surpass any ground based telescope? After the first run, do a second and third scan, with perhaps a year or two between runs. With a bit of analysis - software or otherwise - it should be possible to develop a detailed _dynamic_ picture at various scales. This would essentially present a huge opportunity for both, professional and amateur astronomers. Almost like everybody having their own hubble?

Ok, first for 50 people you may be in a good place to take up managed filtering. Check out Postini, MessageLabs and Email Systems to name a few. These are professional top quality managed filtering services. This is $2-4 per user per month and includes anti-virus, anti-phishing and such. This is also extremely easy to set up and remember, somebody else is running it for you. This is utter bliss really.

I am personally using my own mail server and I did the simplest possible thing - every incoming connection is checked against dnsbls: sorbs, spamhaus and spamcop (all three allow you to look up addresses for free). This blocks nearly all spam and after nearly a year I've never had a false positive.

If you are into setting up and running something yourself, you can use spamassasin (free oss). This is not terribly hard to set up, but worried about false positives I never really used it. I am filtering for a small number of savvy people using Thunderbird...

Speaking of which, thunderbird has a reasonably decent filtering feature. It takes a while to 'learn' but it has been quite useful in filtering out the few leaking spam messages from dnsbls.

There are countless commercial packages and I bet somebody else will cover that. Hope this helps