Tried searching around a little but what I wanted didn't come up.
[xbox 360 version, no mods or console commands]
I've tried to reverse pick pocket like I did in fallout 3 but it says "You cannot place items in container when pickpocketing."
Is there any way to give NPC's items?
Maybe drop them on the ground and somehow they'll pick it up?
Or place it in their house and sooner or later they'll equip it?

If the item is zero weight ( poisoned apples ) then you can place it in their inventory.
Also if the person has no weapon dropping a weapon and then attacking them will make them pick up the weapon.
Be sure to have them at a high disposition before you do this as when you yield they might not accept.
Hope this helps.

I often reverse pickpocket a zero weight mage's hood. The enchanted one I gave Martin before the big fight was helpful, and it went well with his outfit.

Here's a list of zero weight items. Of course enchanted bound weapons are always good to go. http://www.uesp.net/wiki/Category:Oblivion-Items-Zero_Weight

I tried reverse pick pocketing an enchanted mage's hood, but when will the NPC equip it?

NPC will equip things in alphabetical order, they say name it AAA then some word after it.

In Martin's case, apparently he suits up in armor before the big battles. He would not wear the hood with his robe on. But heading for battle he switches equipment, including donning the hood.
If you are sneaky, you can find sleeping bandits in no armor. Slip an enchanted hood (Shock Damage 5pt) into their inventory. Then wake them up for a fight. :shocking:

P.S. - Its good for a laugh. But too much bother for me to lug the hood around in my inventory for that rare chance. :shrug: