iPhone/Android/Windows Mobile: Photoshop.com, the online home of Adobe's market-leading image editor, has released a native photo editor and photo uploader for Android phones, and it's a fairly versatile solution for fixing or offloading images while you're out and about.
On Android phones, photos can be cropped, rotated, resized and adjusted for saturation, exposure and tint, as well as have a soft focus or black & white effect applied. Multiple effects can be undone and re-done, and if you're concerned about making a bad choice, you can upload any pic to a Photoshop.com account first. The iPhone version has a few effects and pre-set colour changes — along with multitouch functionality, of course — and the Android version features a non-multitouch straightening tool, but the two are basically the same app in different shells. All versions are fairly robust for mobile editing apps, and do a good job of correcting the most notable failings of mobile lenses.
Photoshop.com Mobile is a free download for iPhones, Android or Windows Mobile devices.