What do you mean by "offline or online captcha work"? Are you talking about data entry work? Or, are you looking for to find a captcha code for your website?
you might look at elance.com and rentacoder.com and getafreelancer.com - there are jobs for dataentry on a regular basis (especially rentacoder). Getafreelancer is probably #3 of those so you might want to start with elance and rentacoder and see how things work out there. Have you done dataentry before? If so, has it been offline or online? You mentioned "captcha" dataentry work - that indicates it must have been online as well. What type of work did you do? Was it signups to various websites? If so, what type of websites?