There are various galleries which enables us to view beautiful websites & get inspired.
In general, these websites are categorized & presented by their purposes/functions like blogs, business, portfolio, etc.
CSSbake has a different point of view & categorizes websites with their ingredients such as:
which is a good way for anyone who is trying to find good practices on specific elements of a website.
UI Pattern Factory is both an user interface design pattern library and UI gallery where it is possible to find the best practices, get inspired, and share your solutions with others.
The website is mostly focused on web-based business applications & shares patterns like:
UI Pattern Library is also a place where you can ask & vote for new pattern ideas in their forum or add new images to the currently published ones via Flickr.
Well-categorized design patterns are great resources for inspiration. You can easily see how "others" found a succesful way for common design problems.
UI Patterns is an online library which shares design patterns in various categories like:
Also, you can easily contribute to the content & check out the UI Patterns blog which has informative posts.
INSPIRE is an online publication of Adobe Experience Design Team which will attract anyone into software, web & graphic design.
The team shares valuable, real-life experiences both written & via videos.
To give a better idea about the resource, here are some of the recent content published:
INSPIRE is updated regularly & you can find something new almost everyday.
Fluid is an open source software community that:
They have ready-to-use solutions that will attract both designers & developers.
A set of rich, reusable, accessible web UI components. They are built with usability and accessibility in mind. All are unobtrusive & degrade gracefully.
Some of the components are:
A resource presenting design patterns in detail. Currently, it is not a huge library but updated regularly & will be very handy in the future.
A guide on user-centered design (UCD) techniques you can use to learn from your users and design better user experiences.
It has information on a variety of UCD practices, from performing user research and creating models (such as personas and scenarios to inform the design process) to performing UX walkthroughs and user testing of your website or application.
Infragistics Quince, a website with a stunning interface (built with Silverlight), is presenting user experience design patterns in a well-categorized format.
There is a wide list of patterns that vary from breadcumbs to alternating row colors and dashboards to forms.
Even if the content is not what you are looking for, the usability of the website offers a quality UX inspiration.
Pretty Loaded is a website, created by Big Spaceship (a creative agency with amazing Flash works), which is a new source of inspiration to Flash developers.
It simply presents beautiful Flash preloaders as a slideshow.
It displays the company who created it, the client & the year it is done.
You can filter the preloaders by years & nothing much to do rather than just watching 
.
P.S. Thanks to Dave for the suggestion.
Bad Usability Calendar is a calendar displaying "user interface design tips" with a sense of humor.
It has examples of exaggerated use of fancy Web 2.0 design, cover flow, personalization, pull-down menus and more…
It is presented in multiple languages, various sizes & PDF format.
MephoBox is a website displaying quality website interfaces with a well-categorized presentation.
MephoBox is free to use but anyone can register & add new designs to the collection.
It is definitely a nice & growing inspiration resource for any web designer.
The grid, which helps designers to organize text & images in a rational way, is hard to get used to, but after that, it makes most design related problems disappear.
The Grid System is a resource on grid based designs.
It is a very fresh website but already presents handy InDesign & Photoshop grid templates, interesting tools like Syncotype, Phiculator & more.
