So your business is all setup, you have grown your team and your business is making money. You should reinvest in your business to keep it growing, here are some ideas

1. Do you have the perfect domain for your business? If not consider buying one. (We started as agiliqsolutions.com, and bought agiliq.com later)
2. Build links to your site. You already have a headstart in this by blogging and your open source work. Now is the time to take this a notch up. You should ask your team to guest post, and build relationships with other sites to build links.
3. Build relationships with other related businesses. You have been doing this, but be proactive now. Use linkedin, twitter to find people in related industry.
4. Upgrade your equipment (computers, printers and such)
5. Invest in advertising in paid media(Google Adwords, Facebook) and check if you get a positive ROI. (I did not get a ROI but I ran a test.)
6. Is a website or a business related to your business being sold? Why not buy it?

These are just some ideas. The key takeaway is that there can be lot of areas where you can spend money to build a stronger business. Investing in your business is the best investment you can do.