Priemus, those photos of your friends brew session? What is the plant he is cutting to make the filterbed in his mash?
I too was inspired from gruitale.com to make my own gruit ale. I've done 2 iterations on my recipe now, with a 3rd planned for this summer. Last year's came out well, and I enjoyed it very much. I want to get this 3rd try under my belt before posting the recipe, as I feel adding some yarrow flowers to the fermenter will really make this a great brew!
Basically, I decided to start with a scotish old ale recipe, because I wanted something with a malty profile as a base. I skipped the hops, and put some greater wormwood in the boil for bittering, with a touch of sweet gale. Then, I put more sweet gale and touch of wormwood in the primary after fermentation stopped (like a dry hop).
Be careful of the wormwood. That is one BITTER herb! It will completely kill your tastebuds, so a very little goes a LONG way.
Sweet gale is a delightful herb. Very pleasant and aromatic.
I recently used some yarrow flowers in a mead, and it was also a wonderful aromatic addition. I plan to 'dry hop' with yarrow in my next batch.
It will also take a few months of aging to allow the gruit herbs to mellow out in the brew. Young tastings can be very bitter and harsh. I think it really comes out best after at least 6 months.
provided excellent quality herbs ... I would recommend taking a look there.