Lateral Leadership, or How to Lead an Organisation When You Aren't the Chairperson
Suggest Things Off-The-Record
Chat to people about interesting ideas. Suggest ideas to anybody who will 'run' with them - others on the committee etc. Get ideas floating around, and somebody will pick up on them. How will this works depends upon two things - who the people are you talk to and how much you manage to get them to take ownership of your idea. First of all, consider where you plant your ideas. The more energetic and charismatic the person you talk to, the more they are going to be able to do to get people listening and acting on an idea. But talking to the right person isn't often enough - nobody is going to spend too much time simply trying to get you to look good. However, if you manage to feed somebody a half-thought-out idea, and let them flesh it out a little. Once a person feels that an idea is really their own, they will be far more energetic in trying to promote it.
Ask to introduce forums for new ideas to be discussed
Sometimes organisations simply don't 'learn'. A learning organisation is one that is continually trying to improve, think about what it is doing, how things have gone, and stimulate ideas for new projects. Sometimes introducing 'learning structures' is more important than any one idea. If you get frustrated because you can't have an impact, try suggesting a 'new ideas' brainstorm around certain areas at the beginning of committee meetings (for example, five minutes to think of new ideas that would 'create community' or 'involve people we've never touched before'). If your organisation doesn't learn from its mistakes, consider asking for ten minutes to discuss how things went afterwards.
Although it can be a bit formal, writing a proposal can be a powerful way to make a point. If you write a few pages about an idea - why, who, how, when, where - you will set the terms of debate. Even if people don't totally agree with what you have written, by setting the agenda, you will often find that your proposal becomes something that people talk about, and eventually do something that is close to what you envisioned. The reason why writing a proposal can be a very powerful way of influencing people is that it sets the framework for thought and people end up pretty much agreeing with you.
If you disagree, say so. Often the best way to disagree is to be a bit subtle about things. Question things that you aren't convinced by. Explore ideas with questions, and as long as you don't get too annoying people will start to think about things. For example if you aren't sure that something is worth the money, ask if it is really worth it, or are there other things the money could be used on. That kind of thing. Once you have exhausted the 'question' route, just come out and say you disagree. But be able to explain why, or else you won't have much influence on anything.