There’s a nice post up at Macworld about what to do with your old iPad. Lex Friedman does a great job describing options for selling it, giving it away and using the iPad as a dedicated reader, photo browser, etc.
I’ll offer only one suggestion: continue to use it as you ever have. Or get it into the hands of someone who will. The original iPad is still [1. It’s funny to say “still” as the original iPad is only 11 months old.] a fantastic machine that will continue to engage and delight its user(s) for a long time.