I work with Dan Glazer on the Coming To America Mini-Accelerator helping UK companies expand to the US.
The day is free of charge and requires no equity from participants. Instead, it "accelerates" companies' progress in that we walked them through the visa process (new programme for entrepreneurs!) with the people who actually issue the visas to the US, gave them an hour with me to hone a 30-second pitch for the market, highlighted legal minefields others have walked into, and gave ideas on access to finance.
I don't usually work with Service Providers: my experience has been that they want to take from high- growth companies far exceeds the value they offer. Although marketing and new client acquisition is always part of the thinking in any business, with Dan at Fried Frank, they have been giving at least as much to the London ecology as they have been getting.
I met Dan when I was thrown together with him and his Firm during the last UKTI Digital Mission to New York which they sponsored. The lawyers participated in the pitching sessions and were genuinely concerned with the companies' successes. So much so that Dan enthusiastically came up with one of the tag lines that one company still uses to represent itself. It's hard not to like Dan.
Here's some more free information on legal issues to look out for, in the event that you're working with Open Source systems, or considering it. This goes for large and small companies -- the issues are the same and can get quite complex.