M_Boats: GPS

I feel as though I've been asleep like Rip Van Winkle for many years. While I wasn't sailing much, GPS became a relatively inexpensive tool, not to mention cell phones. I see a handheld GPS for sale this morning at Target for $89. Figuring speed sounds nice, but other than getting lost in the fog, what can I do with GPS when I'm sailing on Puget Sound in an area I know with good navigational markers? Dad had one on his fishing boat but he kept a log of where he found the fish or where he dropped the crabpots. Would I use one for more than measuring speed over land? And how would I use it? (Do charts have GPS coordinates?) Bobbie