The trademark registration system is pretty ancient, so it's no surprise that technology trademarks wind up in some unusual categories.
Indeed, most PC companies would logically reside in category 9 in the International Schedule of Classes of Goods and Services, a category which also includes fire extinguishers and vending machines.
Nonetheless, some registrations still seem pretty stupid. Microsoft, for instance, has US trademark registrations in categories 9, 35 (business administration) and 38 (telecommunications), all of which seem relevant enough. But it also has trademarks in category 21, for beverage coolers, and in category 18, for (and I quote) "luggage, tote bags, umbrellas, athletic bags, duffel bags, fanny packs, and knapsacks".
No doubt the Microsoft Company Store does a brisk trade in MS-branded mugs and fanny packs (ahem). But there's a small part of me that thinks that a technology company which can be bothered getting its lawyers to register that kind of trademark is spending a bit too much time thinking about general corporate waffle, and possibly not enough time thinking about building decent products and shipping them on time.
In Microsoft's case, that almost seems a self-evident proposition.