I think I'll join in this year!
I have absolutely no objection to second-hand items, if they're in decent condition. But something that is ratty and gross is also okay if (a) the coolness/weirdness/rarity of the item offsets the bad condition or (b) the rattiness and grossness is the whole point of the item.
General: Weird stuff, especially weird old stuff, is good.
Books: See above. I have a particular love of unusual old books about languages (duh), and Armenian and artificial international languages are especially welcome. Whackadoodle pseudo-science is also good.
Knick-knacks: Weird and/or creepy things are good. Skulls, snakes, dragons, or triceratopses (even cute ones) will fit my decor nicely. Smaller is better, since I don't have a lot of room.
Clothing: Interesting and funny t-shirts are the cornerstone of my personal style. Engrish t-shirts are especially welcome. Size XL preferred, but I can also fit into an L. Again, second-hand is not a problem; I've bought some of my favorite shirts at thrift stores.
Jewelry: Not really interested in jewelry, unless you're talking about unusual character watches or World War I German military decorations.
Food: I like sweet things, spicy things, and especially things that are sweet and spicy at the same time. Ginger and wasabi are my two favorite elements of Japanese cuisine. No food allergies or dietary restrictions.
Ephemera: I collect interesting postcards (new or used). See my posts in the Recent Purchases Thread for examples.
If people could provide lists of their favorite H!P members (including OGs), I might be able to add some bonus goodies to someone's package…. Some of my favorites are Yaguchi Mari, Kago Ai, Yoshizawa Hitomi, Iida Kaori, Ichii Sayaka, Takahashi Ai, Kamei Eri, Fujimoto Miki, Niigaki Risa, Sayashi Riho, Heike Michiyo, Shibata Ayumi, and Tsugunaga Momoko.