"Asian" condiments and staples

I can't top the awesome edible suggestions already given, but maybe consider some chopsticks and a couple small condiment bowls if they don't already have them; most Asian markets have inexpensive selections of both.

Hoisin sauce is another Asian condiment that has an intense salty, sweet, but spicy flavor. It's great in this Beef with Soba Noodle dish: http://www.healthline.com/health-recipes/hoisin-glazed-beef-soba-noodles

LE BEC FIN, to answer your question, I had the same experience like you – when I first tasted plum vinegar it was very different from what I expected it to be. I do not use it in large quantities, usually a drop of two when I feel like adding a fruity note to a dish. For example, if I am making vinaigrette, I will use rice vinegar and a drop or two of umeboshi, and it will give it a nice fruity finish. I have a bottle of fancy blood orange infused olive oil and like to mix it with umeboshi, it makes for a lovely vinaigrette and also nice glaze for radishes. (This also works with regular olive oil, orange zest and orange juice, without additional $$$.) Sometimes, I toss it over steamed vegetables instead of salt. I make green pea humus with it. Sometimes I add it to broths as a seasoning.

I love Japanese Hon Dashi bonito fish soup stock (and yes… it has MSG), and S&B Nanami Togarashi, which is a great seasoning to have on hand.

Doenjang, a Korean fermented soybean paste that has a rich, strong flavor -- holds it own during cooking, unlike miso, adding great depth not only to Asian dishes, but also to braises, stews, bean dishes, etc. without any Asian ties, especially vegetarian and vegan ones I've tried several brands from our Korean market and all are good. (I get the impression that doenjang is a "commodity" type of ingredient, i.e., there's little if any product differentiation.) ;o)

… forgot to mention, some Szechuan pepper and star anise.

Oh Pegeen, can you be my friend :)
Some of my "Asian" favorites include ume plum vinegar, ponzu sauce, mirin and yuzu kosho. And needless to say, a bottle of nice sake (so that they can make black cod miso and then drink the rest).

Thanks, everyone, for these terrific tips. They're much appreciated. I know my list is a it of a mish-mosh but I was glancing through a few recipes to include in their basket and it seemed to cover at least the basics. I will be printing out your tips and saving them!

Pegeen, here's a link to an article by Eileen Yin-Fei-Lo about buying Chinese ingredients. She names the brands she prefers for some of them. You might find it helpful: http://www.finecooking.com/videos/a-chinese-market-tour.aspx

I stock up on Maesri brand for all the cans of curry paste,

Dried Kaffir lime leaves, lemon grass

Sesame oil- Maruhon
chili paste- Yank Sing
red curry paste- fresh, not canned. Found in clear plastic pouch in refrig section of market,
tamarind concentrate- found in Indian stores, opaque plastic jar with red lid. Thick tamarind paste- like tar. A hard tamarind block is difficulat to work with, and Indonesian Tamarind in jar- is a whole other thing- consistency of jam.
rice wine vinegar- Marukan superior
soy sauce- Japanese- Kikkoman low sodium; Chinese- Superior Soy.
tamari-San J gluten free
coconut milk-Chaukoh
Sriracha- bottle w/ Red Rooster on it, Huy Fong
curry powder- Sun Brand Madras curry powder

in case you wish to research further, Serious Eats has done many tasting panels that include some of your items.

Also, your list is mostly Chinese, SE Asia centric, so i couldn't tell if you wanted to cover Japanese (you do mention soba and miso and rice wine vinegar and soy sauce.)
For Japanese, you might want to find white miso instead of aka/red as a more useful miso, but i may be completely wrong about that. You would, however, want to add ramen, and Mirin, Instant Dashi (i don't use the ones w/ MSG; i use the tea bag-like packets that steep in the water.) and Noodle Dipping Sauce (for cold noodle Summer dishes), and Furokake- which comes in many different combos-for sprinkling on rice, noodles, etc to up the flavor. I like it w/ sesame seeds and nori primarily.

Just to warn you, though I am only speaking from experience here in Boston: Japanese stores are usually the only place i find most japanese items; sometimes they are in Korean markets, but rarely in Chinese markets.

What a lovely gift. Won't they be delighted! If you include a card, you might mention the 1000's of recipes on 52 that they can easily access.

some good dried mushrooms and maybe some pickled vegetables. maybe some chinese sausages. rock sugar. i would definitely pick up a small fine mesh strainer for scooping up the scum on top of soups (this is one of my favorite tools). either 5 spice herb mix or the individual ingredients and some cut down coffee filters to fill them with the 5 spices for adding into soups and making their retrieval easy. what a fun present.

Mirin, Gochujang hot pepper paste, chili oil

My Asian pantry staples include: Red Boat Fish Sauce, Huy Fong Foods Sambal Oelek, Lan Chi Chili Paste with Garlic, Huy Fong Sriacha Sauce.

Kombu, nori, bonito flakes, gochujang, black vinegar, more assorted noodles - various rice, soba and ramen, shrimp paste (maybe?), if you have access to good premade curries those are great for a weeknight meal.

Rice paper for making spring rolls.

I've had a lot of luck following Kasma Loha-unchit's recommendations for ingredients used in Thai cooking http://www.thaifoodandtravel.com/brands.html

Pretty complete list. Optional additions...coconut butter and/or ghee, basmati rice, garam Masala, rose water, orange blossom water, pomegranate molasses, saffron.