Hi guys, I'm hoping someone can help me out with something.

My guild leader is looking for an addon that would allow the guild members to view the contents of the guild bank online, where they could flag the items they wished to use in the future, to prevent others from taking them in the meantime.

I realise that an actual 'addon' won't provide this functionality with the new guild bank system, and that something that pulls the data from the Armoury and updates it directly to a website is more likely - but I can't seem to find anything which provides that - can anyone point me in the right direction, or am I barking up the wrong tree?

If you're talking about the guild vault all you can do is limit the access to the different panes of it.
And let ppl request items via mail to the 1 person who has full access to the vault.

Another option is decentralised guild bank (alts acting as Guild Bank) and then I can highly recommend Duckiebank which has a build in request system

What my GM is looking for is an interface on our website that the guild can use to see what is currently in the Guild Bank, and also put notes against items they'll be using in the near future, to prevent someone else taking them.

I have a feeling that it may be possible by stripping the Guild Bank details from the Armoury, and re-formatting it to present it in a different forrmat on the guild site, but I really don't know enough about XML to be certain.