I am not the most patriotic of people, but I do greatly appreciate the UK public library system. I have always visited my local library regularly, to stock up on general reading material; I enjoy reading greatly, and can get through several books each week. However, until fairly recently, I felt somewhat limited by the selection of books in my local library, which as I live in a small town, is not huge, and I would be tempted to supplement the books I borrowed with online purchases.
However, when I lost my library card a few months' ago, and went to sign up for a replacement, I found that the library now offers online reservation services. If you are not already using these, then I strongly recommend investigating them. You can search your county's library catalogue, find out where any copies of the book you are interested in are held, and if the book is not held at your local branch, summon it to you.
This service costs 85p, at least in my county, but will have the book delivered to your local branch within a few days, if it is not out on loan. I find that using this means that there are many books which I do not now need to buy, and am changing my book-buying approach. Now, I buy those books I have read and decided it is worth owning, as well as those which I strongly wish to read, and cannot find through my library catalogue. (This is sometimes the case for US personal finance or business books, for instance, though most fiction I am interested in is available.) I find that many books I read I may enjoy, or get useful information from, but I really do not need to possess a copy.
Another advantage of the system is that if I feel the need to do some online shopping, as well as other spending-deferral techniques which I will discuss more later, I find that reserving books via the library catalogue is a good, and wholesome-feeling, alternative to buying them.
As well as books, libraries can be a good source of DVDs as well as audio-books on CD. I recently hired, for little over £1, an audio book which lasted for most of a trip to the Lake District and back.
While I am in the library, I may take the opportunity to flick through the magazines they subscribe to - yes, I enjoy Good Housekeeping, especially the recipes - and the various newspapers held there.