How can I improve the quality of a photo taken with a low pixel cellphone?
I would suggest you upload it on your computer and improve it using pixlr(http://www.pixlr.com/).Its free and requires no account or try fotoflexer.com for more better editing(free too!!)
There are loads of articles on this topic on the web. A Google search reveals a lot of them. Here are a few links you can read through.
12 Tips for Improving Camera Phone Photos
Taking Pictures with Camera Cell Phones
Go buy a decent camera and retake the photo.
There some softwares that do this like ADJUSTMENTS/AUTO LEVELS. you can try adobe photoshop,
MAGIX Photo Premium...http://www.garryblack.com/improve.htm
Mobile Photo Enhancer