About a year ago friend of mine asked me how to improve his local business rankings on google, the business is about healthy food ( he has a healthy food restaurant ). I did some web2.0, social signals etc... low volume of work since the keyword is local and not many competition actually. Then he told me he has some forum profiles on some really popular local forums (for my country) and he is active there, we updated signatures & links on profiles, it was about 10-15 forum profiles (he was active or semi active on them). In the time span of about 3 weeks he jumped from #4 to #1 and he is still there without any aditional backlink added since then (ofc he has social signals on daily basis). So I guess yes, they can be worth it.