Yes, a sample would be nice. You can use a something like
<http://www.pixentral.com/> to post the samples.

Questions:

1. Are you comparing a zoomed-in view of the logo in Ai to the final 72dpi output in your browser? Try turning on "Pixel Preview" in AI to get a truer preview of your logo in Illustrator.
2. Is the logo scaled to the intended output size in AI before exporting?
3. Are you using the "Save for WEB" feature in AI? This feature lets you preview several options, side-by-side to determine the best choice, such as transparency, file format, scale, color depth, etc.