Loops can be an interesting alternative.  With the use of low loss tubing and high quality tuning capacitors, it is possible to make very small yet efficient antennas.  At the other extreme, very large wire loops offer possibilities for HF operation on a number of different bands.  But, as antenna modeling will easily show, one can't get gain in all directions with a huge loop.

• A Small Loop Antenna for 160 Meters
  QST June 1993, pp. 32-34
  Effective, low-profile 160-meter antennas present a formidable challenge. Here’s one made from 1 inch copper tubing.
• Honey, I Shrunk the Antenna
  QST July 1993, pp. 34-35, 39
  Three and a half to four foot loop antennas for several of the HF bands from 160- to 10-meters.
• You Can Build: A Compact Loop Antenna for 30 through 12 Meters
  QST May 1994, pp. 33-36
  A low-profile, compact antenna made from copper tubing and using a small D.C. motor to remotely tune the capacitor.
• A Home-Brew LOOP Tuning Capacitor
  QST November 1994, pp. 30-32
  Another loop for 20- through 10-meters using a novel "trombone slide" arrangement as a tuning capacitor.
• An In-Room, 80-Meter Transmitting Multiturn Loop Antenna
  QST February 1996, pp. 43-45. Feedback QST May 1996, p. 48.
  A little wood, some wire and a handful of components can make a directional antenna for indoor use where outdoor antennas are not permitted.
• 40 Meters with a Phased Delta Loop
  QST May 1984, pp. 20-21
  A bidirectional,40 meter 2-element Delta Loop array made from wire and coax provides a better way to snare some DX at modest cost.
• The Loop Skywire
  QST November 1985, pp. 20-22
  An inexpensive, easy to build full wave wire loop for 80- or 40-meters. A classic.
  
• A "One-Masted Sloop" for 40, 20, 15 and 10 Meters
  QST April 2002, pp. 44-46
  A sloping loop that takes up less space and still performs.
• A Balanced, Everyday Approach to All-Band Bliss
  QST April 2002, pp. 47-50
  A noise free loop antenna system
• A Horizontal Loop for 80-Meter DX
  QST August 2002, pp. 30-35