One of the biggest gripes about Smartphone cameras, apart from general quality issues, is the clunky (or lack of) controls over camera functions.
Its easy to fumble over functions like zoom, shutter speed, and aperture size. Fortunately, an army of apps awaits, offering tools and options to give you better control over these variables.
Hipstamatic - the $2 app gives your iPhone camera a distinctly analog feel, producing images reminiscent of cheap-o medium-format cameras like the Holga and Lomo. Hipstamatic offers a variety of lenses and film types from which to choose, including several add-on packs for an additional charge.
Camera360 Ultimate - Similar to the Hipstamatic app, but with more features and available for Android-based phones, Camera360 give you Lomo-like effects, but also adds HDR, high contrast reversal film stock simulation, tilt-shift, selective focus (on compatible hardware), alignment grids, and a timer for self-portraits. $4 from the Android store.
PicPlz - This app offers some basic filters and effects, but the real selling point is its integrated social networing capabilities including fast and simple sharing on Facebook, Twitter, Flickr, Tumblr, and Foursquare, as well as syncing with Dropbox. Available for free from the Android store.
ProHDR - Compatible with 3GS and newer iPhones, ProHDR offers superior control over the HDR default presets in the iPhone 4's native OS and also lets 3GS users in on the HDR fun. $2 in the iTunes store.
Darkroom - One of the biggest knocks against the iPhones integrated camera is poor low-light performance. Darkroom helps you snap better photos in dim situations by lessening blur cause by insufficient lighting and accidental motion. Available for iPhone only. Free from the iTunes store.
Adobe Photoshop Express - Not a camera app, per se, but a very useful (and FREE) image manipulation tool for iPhone and Android. Crop, rotate, and touch-up your images, as well as apply filters and adjust color, brightness and contrast.