How to work on multiple ideas?

It's actually quite simple. You have to decide if you want to be an idea man / visionary type of entrepreneur, the builder or the DIY All (Do It Yourself) Bootstrap style of entrepreneur involved in all aspects of his business... If you just want to be idea man no need to build anything...Try to see which one will be the best idea, make a business plan, a quirky prototype and then just search for a co-founder in hopes of getting the first paycheck!

I face the same issue but have noticed a pattern emerge.

I work on one project until I feel sick of it, then I work on the next project until I'm sick of that, then I progress another project and so on. Usually it takes me three to 5 days to get 'bored' of working on one project and about 4 - 6 weeks to return to the first project again.

If you have the money to fund such a slow method of working, don't worry about what other people think and be happy (Plenty of people who suffer from the Protestant Work Ethic will be at pains to criticise, but ignore them and do your thing your way).

Instead, develop the lifestyle that works for you and relax. When we're feeling happy, we are most engaged and 'in the zone'. Obviously that's when we get most done.

Ask yourself what you actually want before worrying about whether what you're doing is 'right' or not. If you simply enjoy doing the activities you're engaging in, all you really need to do is ensure you have sufficient income to meet your needs.

I recommend a book called '4-hour work week' which covers in detail how to go about earning enough to cover your dream lifestyle. http://www.amazon.co.uk/The-4-Hour-Work-Week-Anywhere/dp/0091929113/ref=sr_1_1?ie=UTF8&qid=1347228867&sr=8-1

Something else that will be really useful is to hire a couple of different PA's to help you complete various tasks. By the sounds of it you're an ideas man. What you may wish to have is someone who is a 'completer/finisher' to help push through to completion the different stages of your various projects.

Something helpful for me was reading a line to the effect that 'we're always concentrating, just not always on the same thing for extended periods of time'. So even if our polymath minds focus sporadically on different projects and favoured past times, we are actually completely focussed the whole time. Don't allow people to shoot you down for not focussing!

I also find it helps to be well organised with regards to capturing thoughts so I can turn them into easily actionable steps.

To this effect, I keep a voice recorder by my bed to capture ideas before I fall asleep, during the night and early in the morning. I keep a pen and paper on me at all times when I go out for the same purpose. Periodically I go through my notes and add them to the relevant project files and each project expands and slowly progresses.

I keep only one To-Do list which covers all action tasks for every project. Read 'How to Get Things Done' by David Allen for a great overview of the GTD methodology... It works wonders!

Finally don't give up. Do it your way. Who said you had to do anything anyway?? The only real constrain is having the finances to live as you wish. As mentioned by the previous poster, dry testing each of your money related projects in a rough fashion will very quickly give you the required feedback for advancing the project successfully and quickly.

Things don't have to be perfect to start with. Just work in rough and then with each iteration move toward making your offerings better.

Good ideas for web applications that are going to make money are quite rare. I don't know how talented or visionary you are but I am guessing of your 8 ideas, they aren't all great.

I would decide on the one that is your best, and spend your time on that. Building a money making web application isn't easy, that's why so many fail. Don't make it even harder by only putting part effort into it, that would reduce your chance of success greatly.

As for how to decide which one, you could make landing pages for each with a "register your email to find out when we launch" box. Then do minimal promoting for each and see which one gets the most interest. This will give you a much better gauge than your own gut feeling.

You could also start talking to potential customers about your ideas to validate the, but also that they would pay for it.