Some of the extensions are poorly coded and will cause you and your Magento developer endless headaches. From security risks to overriding existing extensions, right through to slowing down or even crashing your entire site – dealing with bad extensions will cause you endless headaches. Magento connect provides some what of a solution to this issue, however the only way to know if an extension is stable is through trial and error.
So to help you out, below is the list of the extensions we’ve been recommending to our clients. Some are free, some require a small investment.