How can I more easily switch between buffers in Emacs?

M-x customize-group ido then set Ido Mode to Turn on both buffer and file and set Ido Everywhere to on. Then click the Save for future sessions button at the top and enjoy ido magic for both files and buffers. Read the docs to get a sense of how to use ido.

Also, take a look at smex.

UPDATE: iswitchb-mode is obsolete in Emacs >= 24.4, replaced by ido.

All of the features of iswitchdb are now provided by ido. Ross provided a link to the documentation in his answer. You can activate with the following in your .emacs (or use the customization interface as Ross suggests):

(require 'ido)
(ido-mode 'buffers) ;; only use this line to turn off ido for file names!
(setq ido-ignore-buffers '("^ " "*Completions*" "*Shell Command Output*"
               "*Messages*" "Async Shell Command"))

By default, ido provides completions for buffer names and file names. If you only want to replace the features of iswitchb, the second line turns off this feature for file names. ido will ignore any buffers that match the regexps listed in ido-ignore-buffers.

The behaviour described below for iswitchb-mode applies equally to ido for switching buffers.

iswitchb-mode (Emacs < 24.4)

iswitchb-mode replaces the default C-x b behaviour with a very intuitive buffer-switching-with-completion system. There are more sophisticated options, but I've never needed more than this.

After you hit C-x b, you are presented with a list of all buffers. Start typing the name of the buffer you want (or part of its name), and the list is narrowed until only one buffer matches. You don't need to complete the name, though, as soon as the buffer you want is highlighted hitting enter will move you to it. You can also use C-s and C-r to move through the list in order.

You can turn it on by default with this in your .emacs:

(iswitchb-mode 1)

You can also tell it to ignore certain buffers that you never (or very rarely) need to switch to:

(setq iswitchb-buffer-ignore '("^ " "*Completions*" "*Shell Command Output*"
               "*Messages*" "Async Shell Command"))

You can use C-x <right> (next-buffer) and C-x <left> (previous-buffer) to cycle around in the buffer ring. You could bind S-<right> and S-<left> to these functions. (S is the "super-key" or windows-key). This way you can save some keystrokes.

Moreover, note that C-x b has a default entry, i.e. it displays a standard value (most of the time this is the previously viewed buffer), so that you don't always need to enter the buffer name explicitly.

Another nice trick is to open separate windows using C-x 2 and C-x 3. This displays several buffers simultaneously. Then you can bind C-<tab> to other-window and get something similar to tabbed browsing.