For a barrage Ranger, Monk can work to do good damage and/ or to keep you alive with Live Vicariously. You can heal yourself with every hit, on top of the Vampiric bowstring, so getting up to around 8-15 health per hit depending on how heavily you want to invest in Healing Prayers. And in a good solid pack of enemies you're hitting ~5 times per Barrage. Good times
You might run into energy problems with that sort of build though, so zealous bowstring can help in that regard. There aren't really any Monk or Ranger skills that can generate energy for yourself. Some stances/enchantments give energy when you take damage, but unless you're in certain areas where you get spammed with tiny damage attacks you shouldn't get enough to be worth the lack of defense or the enchantment's upkeep.
Overall I don't recommend using too many skills from any subclass, mainly because you have to invest so havily as a Ranger. You need 8-12 Marksmanship depending on your bow and Wilderness and Expertise plug into a lot of stances, preps, skills, you name it. Plus Expertise is great for making your expensive energy skills super cheap, but not for your secondary. For this reason I too suggest Druid's armor... you already have great AL (2nd highest base) and by far the best natural defense against elemental.
Just try to find a couple that supplement your attacks or boost your defensive capabilities without too much investment in energy or attributes.
Judge's Insight sounds good to me, and Heal Area is a nice AoE healer that does good amounts of health (30 + 10 per attribute). Just be sure there's no enemies around or you heal them too!
Here's some skills that my quick scan of the Monk skillset provides:
-Purge Conditions is a great replacement for antidote signet. Takes away ALL conditions for 5 energy. No attributes required.
-Mending is nice but can be pricey in terms of attributes. 3 points for 2 regen, 8 points for 3 regen, or 13 points for 4 regen (not something you can even get with Ranger primary). Possible substitute for Live Vicariously.
Honestly I think the only one you need to worry much about is Judge of Insight. Take Live Vicariously if you want to, for added healing goodness, but it might prove excessive if you have a vamp string. And it's another thing to invest in too. My advice is to use JoI pretty much all the time, Live Vicariously if you have spare attributes, or Purge Conditions if in an area with lots of bleeding/crippling/poisoning/blinding sort of enemies. JoI should be enough.