There are several good resources to help you find local hikes near Portland. OhRanger.com will soon have the ability to search for trails and other points of interest, as we're in the process of relaunching our site with a new database of information and many new features. Right now, you can go to our Where To Go page (http://www.ohranger.com/where-to-go), click on Maine and you'll see all the parks and public lands within the state (i.e. all federal and state managed parks). For example, Wolfe's Neck Woods and Bradbury Mountain State Parks are near to Portland and worth checking out.  Since our trail information isn't yet live, please also check out the following link to localhikes.com for suggestions:  

http://www.localhikes.com/MSA/MSA_6403.asp 

Also, trails.com has lots of good information. Check out this link to hiking in Maine for further ideas:

http://www.trails.com/activity.aspx?area=10428#trailid=MTU068-054&lat=43.70994&lon=-70.23628&zoom=9&...

I hope this helps you have a great hiking experience. Be sure to come back often to OhRanger.com to share your experiences, ask more question and, hopefully, apply your own knowledge to answer questions posed by other park-loving members of our community. Have fun in Maine!