I don't know the law but my understanding was

'you can only work for your sponsor '

buy stocks (but NO day trading), make money from adsense, CJ or linkshare, pyramid business as Amway, buy a commercial property as gas station and make extra income...(as long has you keep you 'status') and Pay Tax

I have not found a single person having problem duing GC due to those extra income. I may be wrong.