Transaction limits among free map APIs have been a hot topic lately.  MapQuest is excited to announce a change to our limits, which includes no preset limit on maps within our free Community Edition license!  In addition, we are setting higher limits on our other service calls (the highest in the industry), with 5,000 geocodes, 5,000 routes and 5,000 search calls allowed per day. In addition to our new transactional limits (or lack thereof!) we wanted to clarify where and how you can use our APIs with a Community Edition license.  You CAN develop paid mobile applications for app stores using our Community Edition licenses.  You can also use SSL. For all the details, check out the following Map API Licensing and Terms Overview.  Also check out the Terms of Use for all the legal specifics.  I've included the handy chart available from the overview below.  Head over to the MapQuest Developer Network to sign up for a free map API key and start developing!
  Licensed Data Licensed Data Open Data
Maps (No preset limit)* (No preset limit)* (No preset limit)*
Directions (No preset limit)* (5000 calls/day) (No preset limit)*
Geocoding (No preset limit)* (5000 calls/day) (No preset limit)*
Search (No preset limit)* (5000 calls/day) (No preset limit)*
Route Matrix (No preset limit)* (5000 route pairs/day) (No preset limit)*
Traffic **  
Non-Commercial or Public Web Apps
Non-Commercial or Public Mobile Apps
Private and/or Paid Commercial Web Apps  
Paid Mobile Apps
Forum Support
Premium Support(24/7 Phone & Email Support)    
System Performance Levels    
Account Management    

* MapQuest operates a shared service and reserves the right to limit access to prevent service degradation.  Please contact MapQuest to discuss applications with heavy traffic volume expectations.

** The Traffic API Web Service cannot be used for real-time navigation, in conjunction with in-car or stand alone portable navigation devices, or be used as the primary purpose of your website or application.