The ability to create your own lists of books and recipes by adding Bookmarks is one of EYB's most powerful features.
My most frequent use is, like many EYB users, searching through my recipes to find ways to use a particular ingredient or two. Often I'll bookmark the recipes in the search results that appeal to me most so that I don't have to repeat it next time, so I have a lot of recipe bookmarks like i.ricotta, i.dill, i.sweet potato, etc. [Because bookmarks display alphabetically, using a letter system for my recipe bookmarks keeps similar ones grouped together, so I'm free to create lots of them without making things chaotic.]
Another very helpful feature is finding out which of my books have recipes for a certain dish, e.g. Brunswick stew, so I can efficiently review the alternatives and decide which to follow (or, more often, come up with a synthesis). Sometimes I bookmark those, so there are quite a few of the form r.slaw, r.bundt cake, r.tomato jam...
When I make a recipe, I add it to my z.made bookmark, and often add Notes. One of my favorite parts of the EYB site is the up-to-the-minute stream of members' notes on recipes and books on the front page. Aside from their intrinsic interest, often they alert me to recipes in books I have that I've overlooked, or spark an idea. Reviewing the z.made bookmark can be a help when meal planning -- or just need a little glow of accomplishment.
To keep a lid on book-buying, I regularly check cookbooks out of the local library. While I'm there, I make a note of any titles that appeal to me for future reading [this is a small college town with a steady stream of new donations and high circulation generally]. Those get added to My Bookshelf in EYB, with a 'library' bookmark. If and when I take out one of them, they get moved to the 'library - checked out' bookmark.
The library lists are examples of the many books on my EYB Bookshelf that I don't actually own; I also have book wishlists organized under bookmarks like 'cuisines', 'preserving', 'home/seasonal', and 'reading'. The books (and magazines) that I do own, less than a third of the ones on My Bookshelf in EYB, have their own 'kitchen shelf' bookmark, so they can be used in the ingredient or recipe searches. But I've sometimes done recipe searches through the libray bookmarks too, when nothing satisfactory turns up in the kitchen shelf search, and have more than once checked out a book to cook a particular dish or two. EYB has turned the library into a handy 'annex' to the kitchen! And has lengthened, but helped me manage, my wishlists.
When I'm reading through a library cookbook, one I've borrowed from a friend, or when I buy a new one, I bookmark the recipes that I want to try, so there are many recipe bookmarks of the form c.Plenty, c.Bombay Kitchen, etc. Way more manageable than Post-It notes! Looking over the recipes in EYB's newly indexed books has also helped me eliminate books from the wishlist, or add to it.
The EYB blog posts on 'recently featured' books and recipes, with links to online versions, are an outstanding way to get more familiar with the content and context of new cookbooks. This morning I was transported by clicking through on some of the gorgeous photos from Southern Italian Desserts, to food blogs with illuminating reports on making the recipes and a solid interview with the author. I am Not A Baker, a cook without a mixer or a springform pan or in fact any real enthusiasm for desserts, but if I were to read one dessert cookbook, this would be the one. EYB efficiently (and attractively) organizes that window to the net.