If you happen to be in Nevada, and especially if you are in the Reno area, you can go on one of NBMG's Earth Science Week field trips, which will be held October 18th and 19th. If you are a geo-type, you can usually sign up to be an unofficial field trip leader. Either way, sign up and go! I will not be able to make it this year because of previous commitments (think: work), but know from previous experience that many of these stops are well worth going to!
UPDATE: Kim lists a number of contests for Earth Science Week, with deadlines coming up shortly - so get cracking if you're interested!
UPDATE AGAIN: MJC Rocks at Geotripper is plugging for taking children on geology field trips; Geology Happens takes some 4th-graders out on a field trip; Tuff Cookie has described Earth Science Week in great detail and with a lot of links, and Lee Allison at Arizona Geology thinks we should all do more for Earth Science Week next year.