For 10+ years we had various generations of in-house built websites. They still did a good job for us. In fact, for the past 5 years, "Web-Site" is the most common selection marked on visitor cards indicating how someone found our church.
This past year, we made the jump to a professionally designed website, and are very pleased with the results. Our analytics reveal a steady increase in visits, and our average visit length is 2:13 (up from :39 seconds with the old website).
I believe there are a couple keys to an effective web-presence:
* Clean, uncluttered front page
* Regularly updated content
One of the things that drives traffic to our website is Facebook and Twitter. We always post a link to the website from our FB page or Twitter acct when a new article has been uploaded, or when promoting an event. Nearly 20% of our weekly traffic link to us from FB or Twitter.
Also, we added Online Giving last year, and it has been pretty successful. There are a couple specific demographics who gravitate to Online Giving:
* Younger, Computer savvy individuals who are active online (they really like the mobile app for online giving)
* Christians who are young in the faith and are just learning how to give have expressed that online giving really helps them. When they get paid, they can give right away, rather than trying to keep the money set aside until Sunday.
We also use our Online Giving company for registrations for events that have a cost attached, such as Youth Outings, Summer Camp, Banquets, etc.
We utilize a Direct Email Marketing service for sending out weekly updates, teachers' memos and registrations for free events (Pastor's fellowships, VBS, etc).