Many of the resources below are free or very low cost, and are sure to be useful to a lot of designers and developers out there.
As always, if we've missed something you think should have been included, please let us know in the comments. And if you have an app or other resource you'd like to see included next month, tweet it to @cameron_chapman for consideration.
Premailer is an online pre-flight app for HTML email creation. Just paste in your URL or source, add a query string to append to links, and add options (like removing unused IDs, comments, or classes), and submit.
Pixa is a $30 Mac app that makes it easy to organize your images into collections. It helps you quickly find and share your pictures, and works with a ton of different image formats, including psd, ai, svg, raw, and many others.
Codifferous helps you review code faster and more effectively. It tracks how much you've reviewed within the source code, and even lets you mark whether each line is accepted or rejected. Public projects are free, while private projects will eventually require a small fee.
Ladda is a UI concept that merges loading indicators into your submit buttons, so that your users aren't left wondering whether clicking submit actually did anything.
Stocksy is a stock photo service that offers high-quality, royalty-free photos that are unlike most stock photos and exclusive to Stocksy. Photos start at just $10.
Tourist.js makes it simple to create guided tours of your app. It includes hooks for things like opening windows or menus, or for waiting for a user to complete certain tasks.
Videry is a curated collection of videos for web designers. There are videos on a variety of topics featured, including CSS, innovation, psychology in design, typography, and much more.
This set of UI Icons comes with 704 minimalist, monochrome icons in the premium version (there's a free version with a more limited set, too). They're all delivered in PSD, AI, EPS, and SVG format, ready to use.
Pure is a set of responsive CSS modules that you can use in all of your website and app projects. It includes modules for grids, forms, buttons, tables, menus, and more.
Bounce lets you integrate Dribbble into your design programs, so you can stay up to date on what's happening without ever leaving Photoshop, Illustrator, InDesign, or Fireworks.
430+ Free Storyboard Illustrations
This collection of 430+ Free Storyboard Illustrations is free for you to use for your personal projects (it's not made to be used in final production projects). It includes a vector file, as well as a PNG file.
SketchMine is a collection of sketch files from the design community. Sketches are categorized by OS, device, icons, mockups, and more.
Guifff is a collection of animated GIFs from Dribbble. There are tons of awesome shots included here, all with permalinks to their respective Dribbble pages.
Red Pen makes it super fast and easy to get feedback from your clients or team members. Just drag your design onto the upload area, share the short URL you're provided with, and get live, annotated feedback. And there's no logging in, project management, or other useless features.
Designers Complaining is an awesome Tumblr blog that catalogs complaints from designers from across the web. Most recently has been a huge number of complains about iOS 7.
Roon is a super simple blogging platform that's cross-platform compatible. It removes 99% of the distractions that come along with blogging, leaving you free to focus on your content.
Need a website for documenting your open source project? Flatdoc is here to help. It lets you create a website fast, using Markdown.
Explore. Create. Repeat.
Explore. Create. Repeat. is an online weekly magazine for the creative community, to inspire and offer insight. You can subscribe by email or read it online.
Popular UIs is a collection of popular website user interface PSDs you can download. These are, of course, recreated for educational purposes only.
Unsplash is a new Tumblr blog offering hi-resolutions photos for your website or other creative projects. They add ten new copyright-free photos every 10 days.
Projecteo is a tiny Instagram projector that works with photo wheels, each holding nine of your Instagram photos. The project is less than $26, and the wheels are each under $9.
Colourcode is a color scheme design tool that lets you select a color by hovering over the page, and then choose a standard color scheme pattern using the slide-out menu.
Six UX is a collection of six second UX videos for inspiration. You can browse depending on what type of UI effect you're looking for, including animation, transition, CSS, iOS, navigation, and more.
Prepros is an app for compiling a variety of languages, including Less, Sass, Scss, Coffeescript, Haml, Markdown, and more. It's available as a Chrome Extension or a Windows application.
The TemplateGen Beta script is a Photoshop script for starting your projects with better templates. You can easily create a new document that includes things like grids, OS X Icon squares, iOS Icons roundrects, and even create your own templates.
Wri.pe is a smart web notepad that you can sign into with Facebook. It includes shortcut keys and Markdown support, is available on any device, backs up to the cloud, and includes calendar-based organization.
Klinic Slab (name your price)
Klinic Slab is a slab serif font in four weights (plus italics). It's a contemporary workhorse that has both personality and functionality.
Albert Sans & Serif (free – $15)
Albert Sans & Serif is a type family that includes both a slab serif and a sans serif font. It's modern and a little bit funky, but still highly legible.
Engine is a free handwritten font with a playful personality. It comes in regular and italic.
Chomp is a playful, fun typeface with a brush script quality. It comes with uppercase characters, numbers, and punctuation.
Gin is a vintage display typeface that comes in eight styles and weights. It's reminiscent of old serif fonts and classic bottles of whiskey and gin.
Lunch Box ($24)
Lunch Box is a unique, handdrawn typeface with infinite customizable options. It also comes with a custom set of small caps, each with four style variations, and stylistic alternatives.
Percival Script (free – $3)
Percival Script is currently a teaser for a script that will be released at a later date. It's downloadable as an EPS file right now, but the full release version will include a sans version, capitals, numerals, and more.
Operator is a slim display typeface that's great as a headline font. It includes 175 glyphs and comes as both a desktop and web font.
Font Awesome 3.2.0 (free)
Font Awesome 3.2.0 has a number of new features, including 58 new icons, pixel perfection at 14px (Bootstrap's default size), and more.
Yuma is an experimental typeface inspired by Navajo textiles with strong geometric patterns.
Know of a new app or resource that should have been included but wasn't? Let us know in the comments!