86% of site visitors arrive at ExcelCalcs via a direct link or bookmark, 12% are referred from other sites and 2% from search engines. I guess this means that users bookmark the site and new users arrive via an existing user's referral in an email link (thanks for this). We seem to get about 10 to 15 new registrations per day but the growth rate is constant whereas I assumed that growth would be exponential (one user invites two...). I know we have only been up and running for 3 months but does anyone have any ideas how to increase the rate of growth? I hope that we can get a virtuous circle of more users, more contributions, more useful site, more users....

You could add a note on your newsletter to forward to a friend so we are all reminded to keep inviting people to the site. Your post have prompted me to invite some more but I have not invited anyone since you first asked me to over two months ago. Three months is no time at all and you are providing a very useful resource for engineers - so I would just bide your time.

Have you ever thought about allowing users to be paid for uploading calculations? There may be a lot of 'time poor' engineers out there who would like to offload some calculations and be willing to pay other users to do them. The site seems quite altruistically motivated, every thing is given away for free, but with financial incentives and a calculation brief to work to you may find that the userbase increases dramatically.
The 'time poor' engineer gets his problems solved, someone gets paid for uploading the calculation and the quantity and quality of repository calculations increases. I have no idea how you could introduce this but it may be the start of a virtuous circle. Keep up the good work.
Mark

I like Mark's thoughts for specific calculations but it would be good to keep some parts of the repository as is so that members feel free to upload and download as they please.

I don't know the technical aspects but could new users be forced to upload a calculation before they can download one?

From the outset I envisaged a Wikipedia type of site where everyone contributed for free and everything is given away for free. I am still committed to the Excelcalcs mission statement "ExcelCalcs will build the web's largest repository of solved problems using the world's most popular mathematical software tool (Excel) and make it available to the world for free." but what I find interesting about Mark's comment is that financial incentives and rewards might expand the number of users and the size and quality of the Repository. I don't think that it conflicts with the mission statement but it will only work if some users are willing to pay for particular calculations. In the first instance I would like to measure users response to see if there would be a demand for this type of service before I embark on developing the new features on the site.

I'm not sure if users will pay for XLC calcs per say but then again companies often employ others for design services so there may be something in it if it is packaged correctly.

You could use its contacts here to offer engineering design services over the internet. But first you need a list of consultants, CVs, testimonials etc and then need to sell this service to companies (perhaps under the Morevision or some other umbrella, operating as an agency but essentially growing your company into an online engineering consultancy with worldwide contacts and resources).

Rather than making this an after thought to excelcalcs.com, I would suggest that you sell this service through a dedicated site (although, as above, this site may prove a useful way to build a list of engineering consultants).