kathrinrich

Generally speaking, no. 95% of all these requests are SPAM. Furthermore, the pages that will actually link to your site are typically buried deep within the linking site and offer no benefit to you.
Another tactic that link spammers use is to remove your link at some point in time leaving them with only inbound links which is the most favorable.
The exception to the rule is exchanging links with an industry relative site that is legitimate. Do they have a phone number? You may actually want to call them and discuss the exchange and negotiate for position.
Link exchanges should also be equal. If their link is one click off of the front page, yours should be too, not buried 5 pages deep in a site directory.