Well, 2 of the most serious ones anyway : travel and reading.
Check out Literary Traveller which is a fabulous site that combines real books and the places they talk about. Great source material for dreaming, researching, planning and drooling. Very bad for that ever-growing pile of books beside my bed.
Personally, I find reading about places both before you go (and while there) is one of the best ways to get a deeper and more meaningful travel experience. It's indispensible for the independent traveller (ignore this if you prefer package tours). Paul Bowles in Morocco, Hemmingway in Pamplona, Kazantkasis in Greece, and a whole host of travel writers about various places have heavily influenced my experiences and understanding of various countries while travelling. You can't really go wrong with engaged reading though you need to get your nose out of the pages and actually talk to people while you're there.
And it beats the crap out of all your info coming from Lonely Planet.
Oh and while you're at it check out why you shouldn't just be reading travel guides when you go from Robert Pelton ('cause he's right on the money when he says they kill what they love).
(and before you ask, the picture is one I took near the Temple of Poseidon, Cape Sounian, Greece notable for the poem Shelley wrote about it)
playing : Psyche Rock (Fatboy Slim Malpaso Mix) - Pierre Henry remixed by Fatboy Slim