Items any MP will want to sell their soul for and that new MP players should be aware of the existence of:
NB: Feel free to add to the list and keep it off buffing items. Weapon choices are already well covered in X's guide. Keep in mind to try and target the list at starting/low level Meta-Physicists.
Nanos:
Mezz
The psychosis pet (mezzpet) can not be found in shops. Since the mezzpet is fixed it is worth getting. The nanocrystal (and instructuion disks) can be obtained as mission rewards. Using
Clicksaver.
Lien's Crystalizer and Urns
Those two will allow you to cast an alternate attack pet in the form of a scythe adept skeleton. Both can be found in the Temple of Three Winds. A walkthrough for ToTW can be found
here.
Although the low level revenant pets aren't that good, having them can't hurt. Anyway ToTW contains a lot of goodies in addition to these two that you will want to go there for.
The Temple of Three Winds is accessible only to characters ranging from level 20 to 60.
Saemus Crystalizer and urn
At your level you should know about the place. Walkthrough
here.
Evocation
As above, you should know by the level you'll need them. In case you levelled very fast, the following:
Evocation of Maddening Wrath.
Evocation of Pure Malevolence.
Evocation of the Abomination.
can not be found either in shop or as mission rewards. They only drop off of bosses in dynamic camps scattered throughout Rubi-Ka. The closest the boss is to the nano's QL, the most likely it is to drop it. Be prepared to slaughter lots of bosses though, loot tables contain lots of items.
Check
Nepentheim's map to know where you are most likely to find a dyna boss around the level of the evoc you're dying to get.
Shadowland Nanos
Composite Teachings can be found in Nascence Gardens.
Composite Mastery can be found in Elysium Sanctuaries.
Composite Infuse with Knowledge can be found in Adonis Gardens(?).
Composite Mocham's Gift can be found in Inferno Gardens(?).
Boon of xxx-xxx can be found in Elysium gardens from the nano vendors.
Channel Notum Vein: <Destination> can be found everywhere more or less

Shadowland Soul Fetter/Awaken Shadowland Memory can be found in ?
xxx of Will/xxx of Resolve can be found in ?
Shadowland attack pets can be bought in Inferno Gardens. They have been reported to drop off Hecklers.
Buffing and useful armors or armor type items
Neleb's Robe is one of the sweetest items you can get early on. It's a lot easier to get if you made the mistake of becoming a slave of Omni-Tek.
The item requires you to be level 36 to wear and gives an additionnal 8 points to nanoskills.
A walkthrough for the Steps of Madness, Neleb's home, can be found
here.
The
Cyborg Armor is an NCU armor. No, it's nowhere near the best armor you can wear at that level AC-wise. Now it will give your NCU an interesting boost, which is particularly interesting if you're a Mocham junky and can't yet equip high QL belts and NCU memories. Besides it's very easy to get a full set of that armor as the dungeon is a lot less camped than Smuggler's Den or the Primus Camp. The armor exists only in a single QL (QL 77), is NODROP (so yes, you need to get it yourself or at least loot the mobs yourself, lazy) and requires you to be level 71 for you to wear it. As said it's not the best there is, but hey, if you don't have money for Carbonum and a big guild to support you don't ignore the NCU it can give you. A walkthrough to the
Cyborg Barracks is to be found here.
Buffing Weapons
Pillows can be missioned for. Try to not spend IP on the required skills if possible. This item can only be worn in the left hand and gives a boost to Matter Creation, Matter Metamorphosis and Biological Metamorphosis. The boost varies with the QL of the item.
Robinson Crystals are an MP only item that drops (with a bit of luck) off chests and bosses in team missions. This one is a right-hander. This means it can be dual wielded, say with a pillow in the left hand. As for pillows, don't spend IP to equip if possible. Robinson Crystals boost MatMet, BioMet and Runspeed. The boost depends upon the QL of the item.
Adapted Notum Crystal come in various flavours to boost one nanoskill and other abilities. Those are left hand items that drop off bosses and chests. The boost will increase with the QL.
Pepper Pistol are a quite rare item. They're not impossible to find though but you need either luck or dedication to get them. They don't directly come as weapons but as containers, thus as tradeskill enhanced items. The finished pistol(s) boost BM, MC and MM, the buff varying with the QL of the weapon. You will find the building process of this wonderful weapon by clicking
here.
Pepper Pistols are left hand weapons and use pistol skill (duh?) and as for the others, if pistols are not your weapon of predilection, don't go investing IP in that to equip them.
Old English Trading Co (OET) pistols can be missioned for. They can be equipped in both hands, thus they're a nice addition to a Pepper. Lower quality OET boost Intelligence, higher QL ones have a psychic buff too. Check the databases for the lowest possible QL of the OET with the boost interesting you, as the boost won't change for lots of level although the requirements to equip will dramatically increase.