This week, snap-happy stars shared their beach days, birthdays, and on-set moments through social media. Bar Refaeli posted cute bikini-clad snaps from her recent yacht day in Spain, while Kate Upton sported a white two-piece on the set of a swimsuit photo shoot. Tom Cruise's kids Connor and Isabella explored London by bike together, and James Franco struck a sexy pose while leaning on a car. Selena Gomez celebrated her 21st birthday by sipping mimosas with Ryan Seacrest, while his ex-girlfriend Julianne Hough spent her special day surrounded by family, friends, and pancakes. See their snaps, plus more from Beyoncé, Miley Cyrus, and Rachel Bilson!