Here are some handy Android Apps that every graphic designer must have in their mobile arsenal.
Color Dictionary ($1.99 on Marketplace, 4 stars)

No matter how long you’ve been working in web design, you may still find it difficult to remember or estimate the HEX, CMYK, or RGB value for your favorite hue. Color Dictionary makes it easy to pinpoint the exact shade you want to use with its simple and intuitive interface and comparison tools. It’ll cost you $1.99 to download, but it’s worth every penny.
Adobe Photoshop Express (Free on Marketplace, 4 stars)

Simply put, Photoshop Express is amazing. It’s a wonder Adobe managed to cram so much of the functionality of their award-winning Creative Suite into a mobile app, but somehow they did. Photoshop Express can retouch, crop, filter, and edit photos and images quickly and easily.
SilverEdit Lite (Free on Marketplace, 4 stars)

If you’re looking for a web design IDE custom-built for use on a mobile device, look no further. SilverEdit Lite allows you to whip up pages and preview them regardless of whether you’ve got a 3G signal or not. It also features an FTP client to upload files to your server if they’re production-ready.
Camera Illusion (Free on Marketplace, 4 stars)

Though it’s a bit basic, Camera Illusion is a surprisingly powerful way to modify images for graphic design purposes. Giving you the ability to apply filters, change colors, and use common effects with your photos, it’s a great way to tweak pictures for a different look. Free and easy, it’s definitely worth your time to check out.
View Web Source (Free on Marketplace, 3.5 stars)

This one’s geared more towards front-end web developers. At least once a day, you probably see something cool on a website and wonder how their developer pulled it off. Checking source markup is easy with View Web Source. It provides users with the ability to look at HTML files, a feature that’s not readily available in most mobile browsers. You can also search for specific text within source files on the fly.
Photo Enhance (Free on Marketplace, 3.5 stars)

If you need a higher level of refinement when it comes to editing photos on your Android, Photo Enhance is the tool for you. You can rejigger white balance, saturation, contrast, detail, and more with its uncomplicated controls. Photo Enhance allows you to produce amazing pictures without having to buy an expensive DSLR camera.
Photobucket Mobile (Free on Marketplace, 4 stars)

For both designers and photography lovers everywhere, Photobucket is one of the best photo-sharing services on the web. Photobucket Mobile gives you the power to upload pictures via a wireless Internet connection, share albums with your buddy list, and find terrific images and photos from your mobile phone quickly and easily. It provides much of the same functionality you’d get from accessing your Photobucket account on a PC.
Magic Color Picker (Free on Marketplace, 4 stars)

One of the most highly-rated applications on the Android Market, Magic Color Picker is the creative professional’s best friend when it comes to crafting outstanding designs. It features a standard color wheel for selecting the proper color you want, as well as sliders to target the perfect shade in HEX, HSL or YUV formats. Considering the fact that it’s free, there’s no reason not to give it a shot.
SketchBook Mobile ($1.99 on Marketplace, 4.5 stars)

Brought to you by a little company called Autodesk, SketchBook Mobile is a full-featured sketching and painting program with a multitude of applications. You’ll need a 1 GHz CPU and at least 512 MB RAM to run it, but it’s only $1.99 if your phone can handle the requirements. It allows you to mock up layouts, create drawings, and storyboard designs on your tablet or smart phone.
Fontest (Free at Marketplace, 4 stars)

We’re all aware of how important unique, distinctive typography is to good web design. Fontest gives designers the ability to see how their fonts render on mobile devices running Android. Featuring support for TTF and OTF font types, smooth resizing, and one-tap uppercase-to-lowercase switching, it’s a must for every font fanatic. As an additional bonus, it’s also 100% free.