Unfortunately, the lightsaber, neuralizer, iron man armor, and sonic screwdriver would all eventually run out of batteries, and somehow I doubt they run on 1.5v alkaline cells. Also, it's doubtful that with our current technology we'd even be able to power a replicator with less than a dedicated nuke plant... so those are all rather less than practical.
Not too sure how the TARDIS is fueled (not a big Dr. Who fan), and the Hitchhiker's Guide has somewhat limited functionality for someone on Earth when it's not about to be demolished for the sake of a space lane...
So I guess I'll go for the TARDIS, purely out of my ignorance as to its fuel source. Hopefully I'll be able to use it to go get some fuel somewhere that isn't Earth... either that or it has fuel that will last long enough to make such a concern a non-issue.