Here is a simple radio that is easy to build and inexpensive. In fact, you probobly have all the parts you need in your junk box. You'll be suprised at the great reception with this little set.

Notes:
1. The antenna can be a piece of wire or a telescoping antenna. 18 inches is a good length for in the city.
2. The tuning capacitor is a regular broadcast band tuning capacitor. I got mine from a junked AM radio. I got the loopstick antenna from that same radio.
3. You can change L1 and C1 to recieve different bands (eg. Shortwave). To recieve shortwave, try this: Make L1 30 turns of 30 guage wire wound on a film can and make C1 a 10-365pf capacitor.
4. Combine this circuit an amplifier for a really neat radio.

Source: http://www.aaroncake.net/circuits/radio.htm

1 x Tuning Capacitor (C1)
1 x 0.1uf Disc Capacitor (C2)
1 x 10 Meg 1/4 W Resistor (R1)
1 x 1N34 Germanium Diode (D1)
1 x 741 Or Similar Op Amp (U1)
1 x "Loopstick" Antenna (L1)
MISC: IC Socket, Crystal Earphone, Wire, Antenna