There is nothing wrong in trade-mark law using the Calgary Tower silhouette in the logo.
I looked up the trademarks, here are links to the two trade-marks which include design elements:
http://www.cipo.ic.gc.ca/app/opic-ci...tIndexOnPage=1
http://www.cipo.ic.gc.ca/app/opic-ci...tIndexOnPage=1
First of all, its clear the silhouette in our logo is not a copy of the silhouette in the designs that are trademarked. Second, the protected wares and services with those designs do not include anything to do with discussion boards--- so on that level, using the tower is not against the law.
There's more to it than that however, you may face a type of passing off allegation, where the owners of the Calgary Tower say having that silhouette in the logo leads others to believe we are associated with the tower, or they endorse us, etc.
So maybe its not worthwhile to go down that path anyway.
There is a bigger problem with this and some of the other logos though, and that is, calling the board "The Unofficial Calgary Flames Community" or anything with the words "Calgary Flames" in it as a logo could get some push-back from the Flames. If it hasn't been done already, someone (ie. Bingo) should ask the Flames if they take issue with a slogan which uses the word "Calgary Flames" in the title. I know it says "Unofficial" to show we're not endorsed or affiliated, so could be a type of fair-use issue, but I think it would be best to seek permission before adopting it.