I wanted a view that showed projects with a few subtasks underneath them. That way, I could quickly scan my projects and make a little progress on each of them. Here’s a sample of the output showing a few of my projects:

Headlines with TAGS match: +PROJECT
Press `C-u r' to search again with new search string
  organizer:  Set up communication processes for Awesome Foundation Toronto
  organizer:  TODO Announce the next pitch night
  organizer:  TODO Follow up with the winner of the previous pitch night for any news to include in the updates

  organizer:  Tidy up the house so that I can find things quickly
  organizer:  TODO Inventory all the things in closets and boxes         :@home:
  organizer:  TODO Drop things off for donation                       :@errands:

  organizer:  Learn how to develop for Android devices

Here are the user-defined functions that set this up:

(defun sacha/org-agenda-project-agenda ()
  "Return the project headline and up to `sacha/org-agenda-limit-items' tasks."
  (save-excursion
    (let* ((marker (org-agenda-new-marker))
           (heading
            (org-agenda-format-item "" (org-get-heading) (org-get-category) nil))
           (org-agenda-restrict t)
           (org-agenda-restrict-begin (point))
           (org-agenda-restrict-end (org-end-of-subtree 'invisible))
           ;; Find the TODO items in this subtree
           (list (org-agenda-get-day-entries (buffer-file-name) (calendar-current-date) :todo)))
      (org-add-props heading
          (list 'face 'default
                'done-face 'org-agenda-done
                'undone-face 'default
                'mouse-face 'highlight
                'org-not-done-regexp org-not-done-regexp
                'org-todo-regexp org-todo-regexp
                'org-complex-heading-regexp org-complex-heading-regexp
                'help-echo
                (format "mouse-2 or RET jump to org file %s"
                        (abbreviate-file-name
                         (or (buffer-file-name (buffer-base-buffer))
                             (buffer-name (buffer-base-buffer))))))
        'org-marker marker
        'org-hd-marker marker
        'org-category (org-get-category)
        'type "tagsmatch")
      (concat heading "\n"
              (replace-regexp-in-string "^" "  "
                                        (org-agenda-finalize-entries list))))))

  (defun sacha/org-agenda-projects-and-tasks (match)
    "Show TODOs for all `org-agenda-files' headlines matching MATCH."
    (interactive "MString: ")
    (let ((todo-only nil))
      (if org-agenda-overriding-arguments
          (setq todo-only (car org-agenda-overriding-arguments)
                match (nth 1 org-agenda-overriding-arguments)))
      (let* ((org-tags-match-list-sublevels
              org-tags-match-list-sublevels)
             (completion-ignore-case t)
             rtn rtnall files file pos matcher
             buffer)
        (when (and (stringp match) (not (string-match "\\S-" match)))
          (setq match nil))
        (setq matcher (org-make-tags-matcher match)
              match (car matcher) matcher (cdr matcher))
        (catch 'exit
          (if org-agenda-sticky
              (setq org-agenda-buffer-name
                    (if (stringp match)
                        (format "*Org Agenda(%s:%s)*"
                                (or org-keys (or (and todo-only "M") "m")) match)
                      (format "*Org Agenda(%s)*" (or (and todo-only "M") "m")))))
          (org-agenda-prepare (concat "TAGS " match))
          (org-compile-prefix-format 'tags)
          (org-set-sorting-strategy 'tags)
          (setq org-agenda-query-string match)
          (setq org-agenda-redo-command
                (list 'org-tags-view `(quote ,todo-only)
                      (list 'if 'current-prefix-arg nil `(quote ,org-agenda-query-string))))
          (setq files (org-agenda-files nil 'ifmode)
                rtnall nil)
          (while (setq file (pop files))
            (catch 'nextfile
              (org-check-agenda-file file)
              (setq buffer (if (file-exists-p file)
                               (org-get-agenda-file-buffer file)
                             (error "No such file %s" file)))
              (if (not buffer)
                  ;; If file does not exist, error message to agenda
                  (setq rtn (list
                             (format "ORG-AGENDA-ERROR: No such org-file %s" file))
                        rtnall (append rtnall rtn))
                (with-current-buffer buffer
                  (unless (derived-mode-p 'org-mode)
                    (error "Agenda file %s is not in `org-mode'" file))
                  (save-excursion
                    (save-restriction
                      (if org-agenda-restrict
                          (narrow-to-region org-agenda-restrict-begin
                                            org-agenda-restrict-end)
                        (widen))
                      (setq rtn (org-scan-tags 'sacha/org-agenda-project-agenda matcher todo-only))
                      (setq rtnall (append rtnall rtn))))))))
          (if org-agenda-overriding-header
              (insert (org-add-props (copy-sequence org-agenda-overriding-header)
                          nil 'face 'org-agenda-structure) "\n")
            (insert "Headlines with TAGS match: ")
            (add-text-properties (point-min) (1- (point))
                                 (list 'face 'org-agenda-structure
                                       'short-heading
                                       (concat "Match: " match)))
            (setq pos (point))
            (insert match "\n")
            (add-text-properties pos (1- (point)) (list 'face 'org-warning))
            (setq pos (point))
            (unless org-agenda-multi
              (insert "Press `C-u r' to search again with new search string\n"))
            (add-text-properties pos (1- (point)) (list 'face 'org-agenda-structure)))
          (org-agenda-mark-header-line (point-min))
          (when rtnall
            (insert (mapconcat 'identity rtnall "\n") ""))
          (goto-char (point-min))
          (or org-agenda-multi (org-agenda-fit-window-to-buffer))
          (add-text-properties (point-min) (point-max)
                               `(org-agenda-type tags
                                                 org-last-args (,todo-only ,match)
                                                 org-redo-cmd ,org-agenda-redo-command
                                                 org-series-cmd ,org-cmd))
          (org-agenda-finalize)
          (setq buffer-read-only t)))))

… and the relevant snippet from my org-agenda-custom-commands:

(setq org-agenda-custom-commands 
      '(
        ;; ... other stuff goes here
        ("2" "List projects with tasks" sacha/org-agenda-projects-and-tasks
         "+PROJECT"
         ((sacha/org-agenda-limit-items 3)))
        ;; ... other stuff goes here
        ))

See this in context in my Emacs configuration.