As president of the Houston ECHO Society (for quite a few years) I have seen things that work and things that don't at least for our club www.w5eco.org
by the way. Here are a few that have worked for us:
Field Day - great way to have people involved in different aspects, learn new things and just have fun
Show n Tell night - we have everyone bring their favorite HT and each person gets a few minutes to tell why Yaesu is better than Icom and not as good as Kenwood....
A December meal get together - we include all family members and have a little gift exchange. One year was hilarious as nearly everyone gave flashlights as gifts, not that they aren't useful.
See if you have a TV station weatherforecaster who is a ham. We have several in Houston and they give some GREAT presentations.
Make sure you use ELMERS and that everyone knows what they are. Pair up experienced people on public service events with newbies. It is exciting to watch someone make their first contact!
Use people in your own club for presentations. If John is a whiz at propagation, ask him if he will do a presentation. If he's shy, pair him up with another.
Have presentations where you show equipment. We did one on power supplies and we did one on antenna tuners. The visual value is incredible.
Build something at a meeting. We built a dipole one night, but had someone explain step by step what we were doing and why it was important.
Develop a list of potential speakers and work up an email and telephone list.
I try to visit with people at hamfests and see if they might like to do a presentation at a club. Sometimes you just have to ask.
Finally, be friendly to everyone at your club meeting, and if they are new, tell them about things your club does and is proud of.
I hope this maybe sparks a few ideas. Have fun out there and if in Houston, the ECHO Society meets the 2nd Monday of the Month. We have a pre-meeting meeting where we eat dinner and brag about each others equipment, etc. just kidding. - Fellowship is another key that has helped our great keep going!