I encourage people to support their local printers whenever possible, but if you prefer to use an online print service, here are two companies I recommend:

1) overnightprint.com

2) vistaprint.com

My recent experience with OvernightPrint.com

I ordered 5000 business cards from OvernightPrint, printed full color on the front and black and white on the back, for about $75 USD including shipping. That's a great deal, and they really do print them overnight. Of course, it takes a few days for them to come in the mail, but overall it was very efficient. One bonus of OvernightPrint is that they print all their cards on extra-heavy cardstock at no extra charge. The heavier cardstock gives your cards a feeling of higher quality.

Beware of Customs and Import Taxes

One thing I should mention about ordering from OvernightPrint or any other US-based company: if you are an international customer you may be charged a hefty customs or import duty. I live in Canada and ended up paying about $25 duty on my order. So my $75 order became $100 in the end.

How to avoid import duties

One way to avoid import duties is to order from an online company that has an office in your own country.

This is where VistaPrint excells. When you go to VistaPrint.com look to see if your country has their own VistaPrint website. In my case, I click on "VistaPrint.ca" (dot ca indicates Canada) and am brought to a Canadian version of the VistaPrint site. Same great service and prices, but no import taxes.

Design Your Logo Online

Both overnightprint.com and vistaprint.com make it easy for you to design your business card online, using either their templates or your own logo.

VistaPrint even offers free business cards

Vistaprint even offers free business cards. The catch is that there is a small line of advertising (it says "you can get business cards like this for free from www.vistaprint.com") on the back of the cards. Depending on what kind of industry you work in, this may or may not be acceptable to you.

Generally speaking, for high priced or other professional services you probably don't want to get the free cards. Some clients and competitors might see you as cheap or an amateur.

However, if this is not a concern in your industry, Vistaprint's free cards are a great deal. The quality is the same as the paid cards.