Adirondack Mountain Club
Appalachian Mountain Club
Catskill 3500 Club
Catskill Mountain Club
Green Mountain Club
New York - New Jersey Trail Conference
Trails NH - links to trip reports and trail conditions all over the Northeast
Views From The Top
Mapping and GPSAcme Mapper - A standby for online topo maps and a sentimental favorite
Breadcrumbs - A webapp for managing and sharing your gps data. I haven't used it much since I have Expert GPS but it seems like a useful tool if you don't want to spend $75(it was a lot less when I bought it!).
CalTopo - online maps with a bunch of neat features
Easy GPS - Basic but free software for organizing your gps data, as well as uploading to and downloading from your gps
Expert GPS - A powerful, feature filled mapping and gps management application. Expensive, but worth it. Full mapping and editing capabilities.
Garmin - Excellent gps units as well as software for uploading and downloading data such as Basecamp and POI Loader.
Google Earth - Excellent for virtual ridgewalking when planning hikes, looking for viewpoints, old woods roads not on the map, etc. You can then draw tracks and add waypoints and export them for use in your gps.
Google Maps - Great for trailhead directions, especially when used in conjunction with smartphones. Create a map in My Places with placemarks for trailheads and open the resulting map on your phone to navigate there. Terrain and satellite views also very helpful for hike planning.
GPS Visualizer - Great webapp for converting various gps files as well as viewing and sharing maps.
PeakFinder - For figuring out what all those peaks you saw were. There is also an Android version for use in the field!
Mobile Apps for AndroidBackcountry Navigator - Wonderful gps and map app for your smartphone. Not really a full-fledged replacement for a gps due to waterproofness and battery life issues but it does allow using real topo maps and aerial imagery that you download in advance, as well as accepting and creating tracks and waypoints. It costs $9.99 but there is also a free demo version so you can try it out first.
Barcode Scanner - A great little QR scanner for use with the trailhead QR codes in my posts. Small memory demand.
Custom Maps - Can create and calibrate custom trail maps from any map you can take a picture of with your phone but also accepts kmz maps you create at home in Google Earth or Expert GPS.
PeakFinder - Excellent for identifying all peaks that you can see around you though I have had quirks with the compass being wrong. Nevertheless, scrolling around the horizon manually works just as well. Costs $3.99. This is the Eastern US version but there are also versions for the Western US, Western Canada, and the Alps. Try the online version first to see what to expect.
Hiking-Blogs Directory - A regularly updated directory to websites and blogs around the world pertaining to hiking