Personally, I am happily employed. I have no need of hunting down a new position. However, I know I'm lucky: I know former colleagues who've been looking for work since 2008. I suspect that some of them just haven't adjusted to the newly shrunk financial sector and are still "living the dream" Credit Boom style. They've been offered jobs but have turned them down because "the salary's not good enough" or "they don't do exactly what I'm interested in".
If you're getting desperate and you need a new role soon, these tactics are for you. Use them with care.
1) Internet Stalking
Thanks to the internet, stalking no longer need involve trailing people physically. These days, you can track them digitally. Find potential hiring managers on Twitter, LinkedIn, or Facebook. Ingratiate yourself subtly. Retweet their opinions; laugh at their jokes.
2) Good Old Fashioned Stalking
Failing this, find out where they hang out and hang out there too. Door-stepping a prospective boss is difficult to execute, especially since the last two years have made high profile financiers paparazzi targets to rival Brangelina (witness Sir Fred Goodwin's hounding by hacks and weirdo leftist protesters alike as evidence of this).
City gyms and sailing club changing rooms are both good. I'd call this the "nuclear option", but you never know, perhaps they'll be impressed at your pure tenacity and hire you on the spot.
The internet can also be a source of birthdates. See the society pages of the Evening Standard, the FT etc. If you send someone a card or email wishing them happy birthday, they may like and remember you. Alternatively, they may think you're weird.
4) Blogs and opinions
People may also be inclined to remember you if you are able to demonstrate a commonality of opinion with them, or at least that you are a person with interesting opinions. Write a blog on your investment strategy. Draw attention to it using LinkedIn, Twitter, or simply emailing your target hirer. Sumzero is quite good for this but note that you'll need to be able to convince the site's founder (Divya Narendra, Harvard buddies with Mark Zuckerberg and recently featured in the Facebook movie) that you're already an "investment professional" in order to be granted membership.
The author is a former M&A banker now working in private equity.