Birders are encouraged to volunteer to assist the International Shorebird Survey project. Shorebirds are counted during spring and fall migration, with winter counts optional.
You don't have to be Super Birder with uncanny abilities to id shorebirds. They're okay with "peeps." From the guidelines:
We cannot always identify all of the shorebirds we see. Often, for example, it is not practical to look at a large flock and identify each of 5,000 Semipalmated Sandpipers. ... Thus, if you identify 100 Semipalmated Sandpipers from among 5,000 peeps, please record them as 100 Semipalmated Sandpipers and 4,900 peeps. If you did not identify any of the sandpipers but presumed they were all Semis, please record them as 5,000 peeps.
Update January, 2018: All data is now entered via eBird's website or mobile app.