Contact local shops and ask for vouchers/freebies then ebay them and tell everyone. Ebay will not charge fees if it is for charity, most local shops will get involved in return for some advertising - particularly for local charities.
Run a sweepstake on lottery bonus ball, grand national, losing weight, swear jar, soaps outcomes, dates of office colleague popping sprog, date you hit your fundraising target, who will win the local kids footy match... anything really. Make the prize one of the shop freebies.
Get persmission from the council, dress up in a costume, collect money in the street in buckets with people who receive the funds. E.g. did this for a local disabled college to fund sports and rehab equipment, I was a fairy, they loved the day out. Made over £700quid in 2 hours in coventry town centre and one random lovely lady bought us all sweeties.
My friend also made up jewellery with bits and pieces from a craft shops, was really easy, really cheap and sold it for loads for the charity.
Had a cheese and wine party once - £15 entry, buy a range of cheap to expensive wines from a warehouse and get some people to bring their faves, spend the evening supping and sipping and you usually have a decent wad (of cash and wine) left over!
Costume at work, stand outside the canteen at coffee and lunch breaks taking peoples change - often in exchange for some handmade stickers or summit.
Print little cards for random occasions and sell them to people at work and running club with funny slogans. e.g. "happy friday", "thinking of you - that's all", "Dear friend, happy easter/valentines/christmas/all saints day - this card covers all celebrations you have in the next year, Love me", "happy sunshine day", "it's raining outside so this yellow card is for your daily sunshine", "happy bonus day", "happy bladder busting monthly meeting day"...
Come Dine with Work Me - had a serious of dinner parties (usually one a week or fortnight) and ask people to pay what they think it is worth. The person who raises the most cash gets a bottle of bubbly and all the cash goes to charity. It's really like eating out at a resturant and paying anyhow!
Ben B - thanks for the tip on a free chairty site - so pleased this is finally happening - I hate using online sites and justifying the % scrape to the host.
I often spend my long runs thinking of ideas to distract me on the long boring bits. Some of the ideas are ludicrous when I think back afterward and some work!