In my knowledge google had not said anything about number of blogroll but they have said this: Ref: http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=35769 I keep not more than 15 to 20 links in blogroll.
Although Google doesn't strictly ask you to limit a certain number of blogroll links on your weblog I would suggest you keep the max outgoing links to not more than 10 links per page. You can keep an infinity number of links on a single page but would you (as a Search Engine) like to open all the thousands of links and read them (index them) while most of them would be just link-exchanged links.
Linking to related sites is great for a few reasons, for instance I do backlink checks on my websites to see who is organically linking to me and I will typically toss the blog/site back a link myself.
how many are you intending to add to your blogroll? If it's for networking purposes, you shouldn't worry about the big G.