Addtional source for telephoto info
Check B-300.com for telephoto and wide angle lenses. They have some comaprisons with the new Oly. TCON-17, the older B-300, and a Sony telephoto lense. They also have the the Olympus CLA-4 tube adaptor (55 mm) for fitting the TCON (or Oly. wide angle) to your C-700. The TCON-17 has 1.7 magnification and is receiving very good reviews. I have not seen much on the new Oly. wide angle (WCON-7 (?) at .7 mangnification). Raynox also makes some respectable add-on lenses.
Check under "Add-on lenses" here at Steve's forum for much better discussion on telephoto lenses than I can possibly provide.
2filters.com, mentioned above, is also a good place to check for adaptor tubes and lenses. They have varying sizes adaptors depending on filter or lense size you're trying to fit to your camera, although I don't think they carry a 55 mm tube if you want to attach an Oly TCON (you could use a step up ring however.)
I have the older Oly B-300, which has been discontinued and "replaced" by the TCON-17. I have been very pleased with the quality of picture from the B-300 on my C-730. I have not purchased a wide angle lense preferring instead to try a panorama.
Paul in NoVA