See thread on newswire F8 3.43pm for different views on this. Though it's understandable not to want one given the police response, I'm gonna suggest the following for people who are coming a long way and would like to meet up with others of similar views.

A compromise suggestion - but see arguments for affinity groups not meeting in bigger blocs - is to meet alongside Anarchist Youth Network since they're not going to have any trouble telling the youth from the non-youth!:

What they suggested was:

gather in London at 12 pm on the South Bank on February 15th for the anti-war demonstration.

This gathering, proposed by London Anarchist Youth, will have the aim of allowing young people to meet others who are interested in anti-authoritarian struggle. We aim to meet, socialise, exchange contacts and then splinter into affinity groups of friends and tackle the day‚s action(s) as a loose network.

If you are interested in meeting up on the day, look for the black flags under Waterloo Bridge (outside the NFT cafe), South Bank from 12pm. This location is easily accessible from Waterloo Station (tube + rail), numerous bus routes and from the Embankment via the Hungerford Footbridge.