Amazon has a huge gift guide broken down into sections including electronics, home goods, clothing, toys and more. It even has sections for geeky gifts, white elephant exchanges, gifts under $20, unique gifts and stocking stuffers.
Or, if you're shopping for men, women, teens, kids 8-12, kids 4-7 or babies, there are entire sub-sections for those, too.
Just follow the links I've included to search each area, then filter down by specific topics for each area by clicking the links at the top of each page. If you pick babies, for example, you can then choose "bath time" or "nursery decor." If you're looking for gifts for kids 8-12, you can narrow down the search by selecting "building toys" or "super heroes."
Also note the small check box on the top-right of the page that lets you narrow for Prime-only results that offer free shipping. And next to that, there's a drop-down that lets you narrow your search by price, too.
So, if you're shopping for a best friend who's 40 years old, you might first choose the gifts for men section, filter down to "home improvement" choose "up to $30" and Amazon will suggest a bunch of useful gifts from a book titled "Home Maintenance for Dummies" to tool kits that are in your price range. And all of the recommendations that I saw were highly rated.