I still use the Pocket Magica book by Green Ronin, as I find that topic books have more interesting takes on Magic Items (or Monsters, or Prestige classes, or spells), and it collects some of the best material from topic books.
The prices need reworking for 3.5, but that's of little relevance to me since I think the Artificer's Handbook take on pricing is a lot more self consistent and gives the DM a lot more flexibility.
Arms & Armor was a hit with my players, but I don't have the 3.5 version yet.
Relics is a book with artifact level items but unlike some earlier books on the topic, gives them to you in 3.xe terms (ahem). I forget whether this was done for 3.0 or 3.5 but really since the items aren't priced, the practical differences are few.
There were some interesting ideas in Forged in Magic, but it was for 3.0. Some of the ideas were over the top and the psionics items are way dated.
The Complete Book of Eldritch Might updates all the items from the three BoEM books to 3.5. Though it's not just a magic item book, I feel that magic items are one of its strengths.
Spells & Magic is also a 3.0 book, but worth looking at. Items in it don't just have that "chinese menu" feel that many 3.x items have, and it remains one of my favorite books on the subject. I was just looking through it yesterday and was amazed by how many cool and off the beaten track items there are in the book, and jotted a bunch down to include in the campaign. It's available in PDF now if price or availability of a hardcopy of an older product is impactical to you.
Not magic items, but Hyperconsious has some neat new psionic items, like psicrystal staves.
