Just started a themed solo-campaign (D&D 3.5)...playing an Indiana Jones based character (i.e. a very knowledgeable explorer of archeological sites obsessed with religious and mystical artifacts). I realize this is old hat *rimshot* but it's the first time at a table I occupied.
The character background is a straight rip & nod, so nothing really to say about that.
As for the build plan I picked Scout for the base class owing to the amount of exploration, running, movement based combat, skills, etc. I also really thought it was important to include the religious/mystical aspect, so included Cleric of Boccob with Knowledge and Magic for my domains which added a TON of synergy, especially regarding knowledge/academia. I felt I had to add one level of Wizard, just for a few spells to aid in 'Indyisms' (like animate rope, disguise self, jump, etc), and because I also really wanted a snake familiar (named him Short-Round). Finally we adapted the Loredelver PrC, allowing for divine spellcasters of non-Illumian descent (something we always thought the class deserved anyway since 'tomb-robbing' is inherently more of a clerical sphere than wizardly).
Nearly all of the planned adventures are research into mysteries, or Tomb Raideresque dungeon delves, all against the backdrop of the world war against the Axis of Evil (Great Kingdom, Iuz, & the Scarlet Brotherhood).
So by the end he'll be a Human Scout 14/Cleric 5/Wizard 1/Lordelver 10 wielding whip and hand crossbow, wearing anachronistic leathers, using spells and skill tricks to create some cinematic goodness. It's not an optimized build by any means, but it's INCREDIBLY fun and very close to true for the character inspiration.
I wish more people played around with themes like this rather than min/maxing. It's crazy awesome. Thinking seriously about requiring it for the next game I run.