Here is a 70cm (440 Mhz) J-Pole antenna that is inexpensive, and easy to build using 1/2 inch copper pipe, and the associated fittings necessary. The dimensions are not typical however, this is what it took to get its SWR low.
http://www.wb8erj.com/440jpole.htm
Here is a 2 meter (146 Mhz) J-Pole antenna that is inexpensive, and easy to build using 3/4 inch copper pipe and the associated fittings necessary.
http://www.wb8erj.com/146jpole.htm
The N6ZAV J-Pole makes a great (but not so hidden) transmitter antenna.
http://www.qsl.net/n6bg/thunt/jpole.html
designed for 89MHz FM frequency.
http://www.solorb.com/elect/microfm/jpole.gif