I don't want to just give him some money, I much rather get something that he can use while he's abroad (all over the place but not cold climates).
Anybody got ideas about the £35(ish) mark?

Travel towel and a baselayer?

big box of condoms.

swiss army knife

Big box of rubbers!

+1

rizla's and a trekking towel.

travel plug

travel towel
light my fire spork or meal kit

book on knot tying and some nice cord to practice on
some nice carabiners
Alpkit Gamma
Petzl e-light

A good penknife or torch.

If he's not an outdoorsy type, how about a posh Mulberry passport cover?

Silk sleeping bag liner / sleeping sheet.

Bed bugs can't bite through silk – most hostels require a liner and it has uses after travelling. I've had mine for about 8 years and have traveled extensively including two RTW trips, and the first thing that I pack is the silk liner.

these guys supply a great range of good value silk bags btw:
http://www.jagbags.co.nz/

Great ideas guys….. keep 'em coming! Oh and he IS very much the outdoors type 🙂

depending on where they are going – mossy net.

This is the one I own and can totally recommend it.

Make sure you get an undyed one or else everything else will get stained by the cheap dye used.

thats one hell of a rubber!!!

my brother got me a pair of bivvy boots for my birthday.

waterproof and warm. You can use them in and outdoors like slippers. Great if youve spent all day in big boots but still need to sneak out to the bog etc.

http://www.needlesports.com/acatalog/Mail_Order_Feet_36.html

From back when I was involved in outdoor shops, there were a few things we always recommended. I reckon they still ring true;
Travel plug (as per Stoner's advice)
Small Petzl (Make sure it takes AA or AAA as they're the most common global size)
Jelly Aerobie – The soft one. Stuffs in a bag and can be great for killing time as well as playing on the beach. Hacky-sacks are good for that as well.
Leatherman and/or Swiss Army knife – Again, as recommended above
Some good travel literature (Try a bit of Bruce Chatwin, some lovely writing)
A Moleskine travel journal/notebook (A Chatwin link, as well as Hemingway!)
Condoms. No joke. Take some.
A door wedge. Seems silly, but in shared rooms/showers etc. a wedge under the door can actually give a little security and privacy!

An option might be to buy a grab-bag of various of those, put 'em all together as a gift.

Turns out he's already got the silk bag liner, but I think the following would make a great present:
Leatherman/knife
Travel Plug
Door wedge
Head torch
and yes some 'armour' (gonna love seeing him open that in front of granny!) 🙂

Thanks everybody – STW collective hit the nail squarely on the head.

Anybody care to suggest a decent well-priced multitool as I can't run to a leatherman and get the other bits as well 🙁

gerber are alright
http://www.shop4gerber.co.uk/gerber_gift_box_sets.html

Have him chipped at the vets… especially if hes going to visit the 'outback' in oz