Nothing beats good family relationships. By this I mean do your best to keep good, honest and open lines of communication with your children. This coupled with clearly defined boundaries puts you in a good position to help then not only make good decisions but also work through the consequences of bad ones.

Software solutions and services:
1) [url=http://www.opendns.org]www.opendns.org[/url]
OpenDNS\'s free solution provides basic protection by filtering our domain names based on their classificaton. All that 

is required is to register with them and then make a simple change to your router/modem\'s DNS. While by no means water-tight, it is a good place to starts and provides a fair level of protection while also keeping track of sites visited and when they were visited.

2) [url=http://www.cyberpatrol.com]www.cyberpatrol.com[/url]
A first class program costing only $40 (US) per year for three computers. Not only does it filter internet content but is a complete computer management tool. It allows you to allocate a set amount of time per day for computer usage based on who is currently logged on and restrict what applications are run. It also keeps a log of what and when sites are visited.

3) [url=http://www.covenanteyes.com]www.covenanteyes.com[/url]
Although not the cheapest solution ($3.50 US, per month, per user) it is a good solution. Basically once the client is installed, the account is set up to e-mail an appointed partner a weekly list of all websites visited. The list is catagorised according to risk. The client does have some issues with IPhones and IPads.

Besides their paid services, they also provide free information on their blog and via an eMagazine.